diff --git a/CODING_STANDARD.md b/CODING_STANDARD.md
index 06c6bf53666..3b62c9b45e4 100644
--- a/CODING_STANDARD.md
+++ b/CODING_STANDARD.md
@@ -182,6 +182,11 @@ Here a few minimalistic coding rules for the CPROVER source tree.
 - Avoid `assert`. If the condition is an actual invariant, use INVARIANT,
   PRECONDITION, POSTCONDITION, CHECK_RETURN, UNREACHABLE or DATA_INVARIANT. If
   there are possible reasons why it might fail, throw an exception.
+- All raw pointers (such as those returned by `symbol_tablet::lookup`) are
+  assumed to be non-owning, and should not be `delete`d. Raw pointers that
+  point to heap-allocated memory should be private data members of an object
+  which safely manages the pointer. As such, `new` should only be used in
+  constructors, and `delete` in destructors. Never use `malloc` or `free`.
 
 # Architecture-specific code
 - Avoid if possible.
diff --git a/src/ansi-c/c_typecheck_type.cpp b/src/ansi-c/c_typecheck_type.cpp
index 1cc2ac95cc0..5cc151ffac9 100644
--- a/src/ansi-c/c_typecheck_type.cpp
+++ b/src/ansi-c/c_typecheck_type.cpp
@@ -208,7 +208,7 @@ void c_typecheck_baset::typecheck_type(typet &type)
       {
         const irep_idt &tag_name=
           to_c_enum_tag_type(type.subtype()).get_identifier();
-        symbol_table.get_writeable(tag_name)->get().type.subtype()=result;
+        symbol_table.get_writeable_ref(tag_name).type.subtype()=result;
       }
 
       type=result;
@@ -782,7 +782,7 @@ void c_typecheck_baset::typecheck_compound_type(struct_union_typet &type)
           type.set(ID_tag, base_name);
 
           typecheck_compound_body(type);
-          symbol_table.get_writeable(s_it->first)->get().type.swap(type);
+          symbol_table.get_writeable_ref(s_it->first).type.swap(type);
         }
       }
       else if(have_body)
@@ -1220,7 +1220,7 @@ void c_typecheck_baset::typecheck_c_enum_type(typet &type)
     {
       // Ok, overwrite the type in the symbol table.
       // This gives us the members and the subtype.
-      symbol_table.get_writeable(symbol.name)->get().type=enum_tag_symbol.type;
+      symbol_table.get_writeable_ref(symbol.name).type=enum_tag_symbol.type;
     }
     else if(symbol.type.id()==ID_c_enum)
     {
diff --git a/src/cpp/cpp_declarator_converter.cpp b/src/cpp/cpp_declarator_converter.cpp
index bdc977eff6f..8e3deb08872 100644
--- a/src/cpp/cpp_declarator_converter.cpp
+++ b/src/cpp/cpp_declarator_converter.cpp
@@ -98,7 +98,7 @@ symbolt &cpp_declarator_convertert::convert(
     }
 
     // try static first
-    symbol_tablet::opt_symbol_reft maybe_symbol=
+    auto maybe_symbol=
       cpp_typecheck.symbol_table.get_writeable(final_identifier);
 
     if(!maybe_symbol)
@@ -191,7 +191,7 @@ symbolt &cpp_declarator_convertert::convert(
     }
 
     // already there?
-    symbol_tablet::opt_symbol_reft maybe_symbol=
+    const auto maybe_symbol=
       cpp_typecheck.symbol_table.get_writeable(final_identifier);
     if(!maybe_symbol)
       return convert_new_symbol(storage_spec, member_spec, declarator);
diff --git a/src/cpp/cpp_typecheck.cpp b/src/cpp/cpp_typecheck.cpp
index 570acc0aa1a..549a5b6d77d 100644
--- a/src/cpp/cpp_typecheck.cpp
+++ b/src/cpp/cpp_typecheck.cpp
@@ -178,7 +178,7 @@ void cpp_typecheckt::static_and_dynamic_initialization()
 
       // Make it nil to get zero initialization by
       // __CPROVER_initialize
-      symbol_table.get_writeable(d_it)->get().value.make_nil();
+      symbol_table.get_writeable_ref(d_it).value.make_nil();
     }
     else
     {
@@ -260,7 +260,7 @@ void cpp_typecheckt::do_not_typechecked()
   for(const auto &named_symbol : symbol_table.symbols)
   {
     if(named_symbol.second.value.id()=="cpp_not_typechecked")
-      symbol_table.get_writeable(named_symbol.first)->get().value.make_nil();
+      symbol_table.get_writeable_ref(named_symbol.first).value.make_nil();
   }
 }
 
@@ -286,7 +286,7 @@ void cpp_typecheckt::clean_up()
     {
       // remove methods from 'components'
       struct_union_typet &struct_union_type=to_struct_union_type(
-        symbol_table.get_writeable(cur_it->first)->get().type);
+        symbol_table.get_writeable_ref(cur_it->first).type);
 
       const struct_union_typet::componentst &components=
         struct_union_type.components();
diff --git a/src/cpp/cpp_typecheck_compound_type.cpp b/src/cpp/cpp_typecheck_compound_type.cpp
index 4796f5e3d76..9818be9176a 100644
--- a/src/cpp/cpp_typecheck_compound_type.cpp
+++ b/src/cpp/cpp_typecheck_compound_type.cpp
@@ -159,9 +159,7 @@ void cpp_typecheckt::typecheck_compound_type(
 
   // check if we have it already
 
-  symbol_tablet::opt_const_symbol_reft maybe_symbol=
-    symbol_table.lookup(symbol_name);
-  if(maybe_symbol)
+  if(const auto maybe_symbol=symbol_table.lookup(symbol_name))
   {
     // we do!
     const symbolt &symbol=*maybe_symbol;
@@ -553,7 +551,7 @@ void cpp_typecheckt::typecheck_compound_declarator(
         put_compound_into_scope(compo);
       }
 
-      typet &vt=symbol_table.get_writeable(vt_name)->get().type;
+      typet &vt=symbol_table.get_writeable_ref(vt_name).type;
       INVARIANT(vt.id()==ID_struct, "Virtual tables must be stored as struct");
       struct_typet &virtual_table=to_struct_type(vt);
 
diff --git a/src/cpp/cpp_typecheck_declaration.cpp b/src/cpp/cpp_typecheck_declaration.cpp
index 988b4de3568..082b5fcbbab 100644
--- a/src/cpp/cpp_typecheck_declaration.cpp
+++ b/src/cpp/cpp_typecheck_declaration.cpp
@@ -105,7 +105,7 @@ void cpp_typecheckt::convert_anonymous_union(
     id.is_member=true;
   }
 
-  symbol_table.get_writeable(union_symbol.name)->get().type.set(
+  symbol_table.get_writeable_ref(union_symbol.name).type.set(
     "#unnamed_object", symbol.base_name);
 
   code.swap(new_code);
diff --git a/src/cpp/cpp_typecheck_expr.cpp b/src/cpp/cpp_typecheck_expr.cpp
index b0a4a450395..0142c44780f 100644
--- a/src/cpp/cpp_typecheck_expr.cpp
+++ b/src/cpp/cpp_typecheck_expr.cpp
@@ -1244,8 +1244,7 @@ void cpp_typecheckt::typecheck_expr_member(
     assert(it!=symbol_table.symbols.end());
 
     if(it->second.value.id()=="cpp_not_typechecked")
-      symbol_table.get_writeable(component_name)->get()
-        .value.set("is_used", true);
+      symbol_table.get_writeable_ref(component_name).value.set("is_used", true);
   }
 }
 
@@ -2203,7 +2202,7 @@ void cpp_typecheckt::typecheck_side_effect_function_call(
            type.id()==ID_code &&
            type.find(ID_return_type).id()==ID_destructor)
         {
-          add_method_body(&symbol_table.get_writeable(it->get(ID_name))->get());
+          add_method_body(&symbol_table.get_writeable_ref(it->get(ID_name)));
           break;
         }
       }
@@ -2372,7 +2371,7 @@ void cpp_typecheckt::typecheck_method_application(
   member_expr.swap(expr.function());
 
   const symbolt &symbol=lookup(member_expr.get(ID_component_name));
-  add_method_body(&symbol_table.get_writeable(symbol.name)->get());
+  add_method_body(&symbol_table.get_writeable_ref(symbol.name));
 
   // build new function expression
   exprt new_function(cpp_symbol_expr(symbol));
@@ -2414,7 +2413,7 @@ void cpp_typecheckt::typecheck_method_application(
   if(symbol.value.id()=="cpp_not_typechecked" &&
      !symbol.value.get_bool("is_used"))
   {
-    symbol_table.get_writeable(symbol.name)->get().value.set("is_used", true);
+    symbol_table.get_writeable_ref(symbol.name).value.set("is_used", true);
   }
 }
 
@@ -2683,7 +2682,7 @@ void cpp_typecheckt::typecheck_expr_function_identifier(exprt &expr)
     assert(it != symbol_table.symbols.end());
 
     if(it->second.value.id()=="cpp_not_typechecked")
-      symbol_table.get_writeable(it->first)->get().value.set("is_used", true);
+      symbol_table.get_writeable_ref(it->first).value.set("is_used", true);
   }
 
   c_typecheck_baset::typecheck_expr_function_identifier(expr);
diff --git a/src/cpp/cpp_typecheck_template.cpp b/src/cpp/cpp_typecheck_template.cpp
index feecc6ea169..6654db1cf3f 100644
--- a/src/cpp/cpp_typecheck_template.cpp
+++ b/src/cpp/cpp_typecheck_template.cpp
@@ -107,9 +107,7 @@ void cpp_typecheckt::typecheck_class_template(
 
   // check if we have it already
 
-  symbol_tablet::opt_symbol_reft maybe_symbol=
-    symbol_table.get_writeable(symbol_name);
-  if(maybe_symbol)
+  if(const auto maybe_symbol=symbol_table.get_writeable(symbol_name))
   {
     // there already
     symbolt &previous_symbol=*maybe_symbol;
@@ -265,7 +263,7 @@ void cpp_typecheckt::typecheck_function_template(
 
     if(has_value)
     {
-      symbol_table.get_writeable(symbol_name)->get().type.swap(declaration);
+      symbol_table.get_writeable_ref(symbol_name).type.swap(declaration);
       cpp_scopes.id_map[symbol_name]=&template_scope;
     }
 
diff --git a/src/goto-cc/compile.cpp b/src/goto-cc/compile.cpp
index 530e074bd88..9ace2924747 100644
--- a/src/goto-cc/compile.cpp
+++ b/src/goto-cc/compile.cpp
@@ -725,7 +725,7 @@ void compilet::convert_symbols(goto_functionst &dest)
       {
         debug() << "Compiling " << s_it->first << eom;
         converter.convert_function(s_it->first);
-        symbol_table.get_writeable(*it)->get().value=exprt("compiled");
+        symbol_table.get_writeable_ref(*it).value=exprt("compiled");
       }
     }
   }
diff --git a/src/goto-cc/linker_script_merge.cpp b/src/goto-cc/linker_script_merge.cpp
index 8d683aa4418..874e51e0d97 100644
--- a/src/goto-cc/linker_script_merge.cpp
+++ b/src/goto-cc/linker_script_merge.cpp
@@ -168,8 +168,7 @@ int linker_script_merget::pointerize_linker_defined_symbols(
   // First, pointerize the actual linker-defined symbols
   for(const auto &pair : linker_values)
   {
-    symbol_tablet::opt_symbol_reft maybe_symbol=
-      symbol_table.get_writeable(pair.first);
+    const auto maybe_symbol=symbol_table.get_writeable(pair.first);
     if(!maybe_symbol)
       continue;
     symbolt &entry=*maybe_symbol;
@@ -190,7 +189,7 @@ int linker_script_merget::pointerize_linker_defined_symbols(
     debug() << "Pointerizing the symbol-table value of symbol " << pair.first
             << eom;
     int fail=pointerize_subexprs_of(
-      symbol_table.get_writeable(pair.first)->get().value,
+      symbol_table.get_writeable_ref(pair.first).value,
       to_pointerize,
       linker_values);
     if(to_pointerize.empty() && fail==0)
diff --git a/src/goto-instrument/dump_c.cpp b/src/goto-instrument/dump_c.cpp
index 2384f225513..6bb3b3644f2 100644
--- a/src/goto-instrument/dump_c.cpp
+++ b/src/goto-instrument/dump_c.cpp
@@ -55,7 +55,7 @@ void dump_ct::operator()(std::ostream &os)
       continue;
 
     code_typet &code_type=to_code_type(
-      copied_symbol_table.get_writeable(named_symbol.first)->get().type);
+      copied_symbol_table.get_writeable_ref(named_symbol.first).type);
     code_typet::parameterst &parameters=code_type.parameters();
 
     for(code_typet::parameterst::iterator
diff --git a/src/goto-instrument/goto_program2code.cpp b/src/goto-instrument/goto_program2code.cpp
index 99444893dfb..70c2cc243b0 100644
--- a/src/goto-instrument/goto_program2code.cpp
+++ b/src/goto-instrument/goto_program2code.cpp
@@ -134,7 +134,7 @@ void goto_program2codet::scan_for_varargs()
     system_headers.insert("stdarg.h");
 
     code_typet &code_type=
-      to_code_type(symbol_table.get_writeable(func_name)->get().type);
+      to_code_type(symbol_table.get_writeable_ref(func_name).type);
     code_typet::parameterst &parameters=code_type.parameters();
 
     for(code_typet::parameterst::iterator
diff --git a/src/goto-instrument/remove_function.cpp b/src/goto-instrument/remove_function.cpp
index f9344f68238..6376b4a5512 100644
--- a/src/goto-instrument/remove_function.cpp
+++ b/src/goto-instrument/remove_function.cpp
@@ -51,7 +51,7 @@ void remove_function(
     message.status() << "Removing body of " << identifier
                      << messaget::eom;
     entry->second.clear();
-    goto_model.symbol_table.get_writeable(identifier)->get().value.make_nil();
+    goto_model.symbol_table.get_writeable_ref(identifier).value.make_nil();
   }
 }
 
diff --git a/src/goto-instrument/wmm/shared_buffers.h b/src/goto-instrument/wmm/shared_buffers.h
index a3b87a26d86..7f946522858 100644
--- a/src/goto-instrument/wmm/shared_buffers.h
+++ b/src/goto-instrument/wmm/shared_buffers.h
@@ -158,11 +158,10 @@ class shared_bufferst
 
   irep_idt choice(const irep_idt &function, const std::string &suffix)
   {
-    symbol_tablet::opt_const_symbol_reft maybe_symbol=
-      symbol_table.lookup(function);
+    const auto maybe_symbol=symbol_table.lookup(function);
     const std::string function_base_name =
       maybe_symbol
-        ? id2string(maybe_symbol->get().base_name)
+        ? id2string(maybe_symbol->base_name)
         : "main";
     return add(function_base_name+"_weak_choice",
       function_base_name+"_weak_choice", suffix, bool_typet());
diff --git a/src/goto-programs/interpreter.cpp b/src/goto-programs/interpreter.cpp
index b3ba928bcca..b2542cbeee7 100644
--- a/src/goto-programs/interpreter.cpp
+++ b/src/goto-programs/interpreter.cpp
@@ -444,7 +444,7 @@ typet interpretert::get_type(const irep_idt &id) const
 {
   dynamic_typest::const_iterator it=dynamic_types.find(id);
   if(it==dynamic_types.end())
-    return symbol_table.lookup(id)->get().type;
+    return symbol_table.lookup_ref(id).type;
   return it->second;
 }
 
@@ -1041,7 +1041,7 @@ exprt interpretert::get_value(const irep_idt &id)
   if(findit!=dynamic_types.end())
     get_type=findit->second;
   else
-    get_type=symbol_table.lookup(id)->get().type;
+    get_type=symbol_table.lookup_ref(id).type;
 
   symbol_exprt symbol_expr(id, get_type);
   mp_integer whole_lhs_object_address=evaluate_address(symbol_expr);
diff --git a/src/goto-programs/mm_io.cpp b/src/goto-programs/mm_io.cpp
index 56313c42201..2ff0ee9da12 100644
--- a/src/goto-programs/mm_io.cpp
+++ b/src/goto-programs/mm_io.cpp
@@ -118,13 +118,13 @@ void mm_io(
   irep_idt id_r=CPROVER_PREFIX "mm_io_r";
   irep_idt id_w=CPROVER_PREFIX "mm_io_w";
 
-  symbol_tablet::opt_const_symbol_reft maybe_symbol=symbol_table.lookup(id_r);
+  auto maybe_symbol=symbol_table.lookup(id_r);
   if(maybe_symbol)
-    mm_io_r=maybe_symbol->get().symbol_expr();
+    mm_io_r=maybe_symbol->symbol_expr();
 
   maybe_symbol=symbol_table.lookup(id_w);
   if(maybe_symbol)
-    mm_io_w=maybe_symbol->get().symbol_expr();
+    mm_io_w=maybe_symbol->symbol_expr();
 
   for(auto & f : goto_functions.function_map)
     mm_io(mm_io_r, mm_io_w, f.second, ns);
diff --git a/src/goto-programs/remove_exceptions.cpp b/src/goto-programs/remove_exceptions.cpp
index a2cfcc10947..a49dcb12a4e 100644
--- a/src/goto-programs/remove_exceptions.cpp
+++ b/src/goto-programs/remove_exceptions.cpp
@@ -134,8 +134,7 @@ void remove_exceptionst::add_exceptional_returns(
   const irep_idt &function_id=func_it->first;
   goto_programt &goto_program=func_it->second.body;
 
-  symbol_tablet::opt_const_symbol_reft maybe_symbol=
-    symbol_table.lookup(function_id);
+  auto maybe_symbol=symbol_table.lookup(function_id);
   INVARIANT(maybe_symbol, "functions should be recorded in the symbol table");
   const symbolt &function_symbol=*maybe_symbol;
 
@@ -255,11 +254,9 @@ void remove_exceptionst::instrument_exception_handler(
     to_code_landingpad(instr_it->code).catch_expr();
   irep_idt thrown_exception_global=id2string(function_id)+EXC_SUFFIX;
 
-  symbol_tablet::opt_const_symbol_reft maybe_symbol=
-    symbol_table.lookup(thrown_exception_global);
-  if(maybe_symbol)
+  if(const auto maybe_symbol=symbol_table.lookup(thrown_exception_global))
   {
-    const symbol_exprt thrown_global_symbol=maybe_symbol->get().symbol_expr();
+    const symbol_exprt thrown_global_symbol=maybe_symbol->symbol_expr();
     // next we reset the exceptional return to NULL
     null_pointer_exprt null_voidptr((pointer_type(empty_typet())));
 
@@ -425,9 +422,9 @@ void remove_exceptionst::instrument_function_call(
   const irep_idt &callee_id=
     to_symbol_expr(function_call.function()).get_identifier();
 
-  symbol_tablet::opt_const_symbol_reft callee_inflight_exception=
+  const auto callee_inflight_exception=
     symbol_table.lookup(id2string(callee_id)+EXC_SUFFIX);
-  symbol_tablet::opt_const_symbol_reft local_inflight_exception=
+  const auto local_inflight_exception=
     symbol_table.lookup(id2string(function_id)+EXC_SUFFIX);
 
   if(callee_inflight_exception && local_inflight_exception)
@@ -436,9 +433,9 @@ void remove_exceptionst::instrument_function_call(
       func_it, instr_it, stack_catch, locals);
 
     const symbol_exprt callee_inflight_exception_expr=
-      callee_inflight_exception->get().symbol_expr();
+      callee_inflight_exception->symbol_expr();
     const symbol_exprt local_inflight_exception_expr=
-      local_inflight_exception->get().symbol_expr();
+      local_inflight_exception->symbol_expr();
 
     // add a null check (so that instanceof can be applied)
     equal_exprt eq_null(
diff --git a/src/goto-programs/remove_static_init_loops.cpp b/src/goto-programs/remove_static_init_loops.cpp
index 794ec547fc4..e9411beeb5b 100644
--- a/src/goto-programs/remove_static_init_loops.cpp
+++ b/src/goto-programs/remove_static_init_loops.cpp
@@ -58,8 +58,7 @@ void remove_static_init_loopst::unwind_enum_static(
         const std::string &fname=id2string(ins.function);
         size_t class_prefix_length=fname.find_last_of('.');
         // is the function symbol in the symbol table?
-        symbol_tablet::opt_const_symbol_reft maybe_symbol=
-          symbol_table.lookup(ins.function);
+        const auto maybe_symbol=symbol_table.lookup(ins.function);
         if(!maybe_symbol)
         {
           message.warning() << "function `" << id2string(ins.function)
diff --git a/src/java_bytecode/ci_lazy_methods.cpp b/src/java_bytecode/ci_lazy_methods.cpp
index 240dafc0e29..b0fc17fb03b 100644
--- a/src/java_bytecode/ci_lazy_methods.cpp
+++ b/src/java_bytecode/ci_lazy_methods.cpp
@@ -144,7 +144,7 @@ bool ci_lazy_methodst::operator()(
         method_converter(
           *parsed_method.first, *parsed_method.second, new_lazy_methods);
         gather_virtual_callsites(
-          symbol_table.lookup(mname)->get().value,
+          symbol_table.lookup_ref(mname).value,
           virtual_callsites);
         any_new_methods=true;
       }
diff --git a/src/java_bytecode/java_bytecode_convert_method.cpp b/src/java_bytecode/java_bytecode_convert_method.cpp
index f6d267ef087..c5076ec235d 100644
--- a/src/java_bytecode/java_bytecode_convert_method.cpp
+++ b/src/java_bytecode/java_bytecode_convert_method.cpp
@@ -893,8 +893,7 @@ bool java_bytecode_convert_methodt::class_needs_clinit(
     findit_any.first->second=true;
     return true;
   }
-  symbol_tablet::opt_const_symbol_reft maybe_symbol=
-    symbol_table.lookup(classname);
+  const auto maybe_symbol=symbol_table.lookup(classname);
   // Stub class?
   if(!maybe_symbol)
   {
diff --git a/src/java_bytecode/java_bytecode_instrument.cpp b/src/java_bytecode/java_bytecode_instrument.cpp
index 1b30f02d037..31c18fab721 100644
--- a/src/java_bytecode/java_bytecode_instrument.cpp
+++ b/src/java_bytecode/java_bytecode_instrument.cpp
@@ -617,5 +617,5 @@ void java_bytecode_instrument(
   // instrument(...) can add symbols to the table, so it's
   // not safe to hold a reference to a symbol across a call.
   for(const auto &symbol : symbols_to_instrument)
-    instrument(symbol_table.get_writeable(symbol)->get().value);
+    instrument(symbol_table.get_writeable_ref(symbol).value);
 }
diff --git a/src/java_bytecode/java_string_library_preprocess.cpp b/src/java_bytecode/java_string_library_preprocess.cpp
index ce053f25185..73200f1fee7 100644
--- a/src/java_bytecode/java_string_library_preprocess.cpp
+++ b/src/java_bytecode/java_string_library_preprocess.cpp
@@ -796,8 +796,8 @@ void java_string_library_preprocesst::code_assign_java_string_to_string_expr(
 
   typet deref_type;
   if(rhs.type().subtype().id()==ID_symbol)
-    deref_type=symbol_table.lookup(
-      to_symbol_type(rhs.type().subtype()).get_identifier())->get().type;
+    deref_type=symbol_table.lookup_ref(
+      to_symbol_type(rhs.type().subtype()).get_identifier()).type;
   else
     deref_type=rhs.type().subtype();
 
@@ -1252,11 +1252,9 @@ exprt java_string_library_preprocesst::get_primitive_value_of_object(
 
   // Check that the type of the object is in the symbol table,
   // otherwise there is no safe way of finding its value.
-  symbol_tablet::opt_const_symbol_reft maybe_symbol=
-    symbol_table.lookup(object_type.get_identifier());
-  if(maybe_symbol)
+  if(const auto maybe_symbol=symbol_table.lookup(object_type.get_identifier()))
   {
-    struct_typet struct_type=to_struct_type(maybe_symbol->get().type);
+    struct_typet struct_type=to_struct_type(maybe_symbol->type);
     // Check that the type has a value field
     const struct_union_typet::componentt value_comp=
       struct_type.get_component("value");
@@ -1502,7 +1500,7 @@ codet java_string_library_preprocesst::make_object_get_class_code(
   // > Class class1;
   pointer_typet class_type=
     java_reference_type(
-      symbol_table.lookup("java::java.lang.Class")->get().type);
+      symbol_table.lookup_ref("java::java.lang.Class").type);
   symbolt class1_sym=get_fresh_aux_symbol(
     class_type, "class_symbol", "class_symbol", loc, ID_java, symbol_table);
   symbol_exprt class1=class1_sym.symbol_expr();
@@ -1539,7 +1537,7 @@ codet java_string_library_preprocesst::make_object_get_class_code(
 
   // string1 = (String*) string_expr
   pointer_typet string_ptr_type=java_reference_type(
-    symbol_table.lookup("java::java.lang.String")->get().type);
+    symbol_table.lookup_ref("java::java.lang.String").type);
   exprt string1=allocate_fresh_string(string_ptr_type, loc, symbol_table, code);
   code.add(
     code_assign_string_expr_to_new_java_string(
diff --git a/src/jsil/jsil_convert.cpp b/src/jsil/jsil_convert.cpp
index 3bc44fa41e1..e2f24aa99a7 100644
--- a/src/jsil/jsil_convert.cpp
+++ b/src/jsil/jsil_convert.cpp
@@ -48,9 +48,7 @@ bool jsil_convertt::operator()(const jsil_parse_treet &parse_tree)
     if(convert_code(new_symbol, to_code(new_symbol.value)))
       return true;
 
-    symbol_tablet::opt_const_symbol_reft maybe_symbol=
-      symbol_table.lookup(new_symbol.name);
-    if(maybe_symbol)
+    if(const auto maybe_symbol=symbol_table.lookup(new_symbol.name))
     {
       const symbolt &s=*maybe_symbol;
       if(s.value.id()=="no-body-just-yet")
diff --git a/src/jsil/jsil_typecheck.cpp b/src/jsil/jsil_typecheck.cpp
index ecc36288bae..c7a8dd97acc 100644
--- a/src/jsil/jsil_typecheck.cpp
+++ b/src/jsil/jsil_typecheck.cpp
@@ -42,8 +42,7 @@ void jsil_typecheckt::update_expr_type(exprt &expr, const typet &type)
   {
     const irep_idt &id=to_symbol_expr(expr).get_identifier();
 
-    symbol_tablet::opt_symbol_reft maybe_symbol=
-      symbol_table.get_writeable(id);
+    const auto maybe_symbol=symbol_table.get_writeable(id);
     if(!maybe_symbol)
     {
       error() << "unexpected symbol: " << id << eom;
@@ -749,8 +748,7 @@ void jsil_typecheckt::typecheck_function_call(
   {
     const irep_idt &id=to_symbol_expr(f).get_identifier();
 
-    symbol_tablet::opt_const_symbol_reft maybe_symbol=symbol_table.lookup(id);
-    if(maybe_symbol)
+    if(const auto maybe_symbol=symbol_table.lookup(id))
     {
       const symbolt &s=*maybe_symbol;
 
diff --git a/src/linking/linking.cpp b/src/linking/linking.cpp
index d71ad02768a..0f89277ff94 100644
--- a/src/linking/linking.cpp
+++ b/src/linking/linking.cpp
@@ -1290,7 +1290,7 @@ void linkingt::copy_symbols()
        named_symbol.second.value.is_not_nil())
     {
       object_type_updates(
-        main_symbol_table.get_writeable(named_symbol.first)->get().value);
+        main_symbol_table.get_writeable_ref(named_symbol.first).value);
     }
   }
 }
diff --git a/src/linking/static_lifetime_init.cpp b/src/linking/static_lifetime_init.cpp
index 4d96670cafd..1b085098e8d 100644
--- a/src/linking/static_lifetime_init.cpp
+++ b/src/linking/static_lifetime_init.cpp
@@ -31,8 +31,7 @@ bool static_lifetime_init(
 {
   namespacet ns(symbol_table);
 
-  symbol_tablet::opt_symbol_reft maybe_symbol=
-    symbol_table.get_writeable(INITIALIZE_FUNCTION);
+  const auto maybe_symbol=symbol_table.get_writeable(INITIALIZE_FUNCTION);
   if(!maybe_symbol)
     return false;
   symbolt &init_symbol=*maybe_symbol;
diff --git a/src/util/config.cpp b/src/util/config.cpp
index 0e8f3d692c8..8b4a6177991 100644
--- a/src/util/config.cpp
+++ b/src/util/config.cpp
@@ -1177,9 +1177,7 @@ void configt::set_object_bits_from_symbol_table(
     return;
 
   // set object_bits according to entry point language
-  symbol_tablet::opt_const_symbol_reft maybe_symbol=
-    symbol_table.lookup(CPROVER_PREFIX "_start");
-  if(maybe_symbol)
+  if(const auto maybe_symbol=symbol_table.lookup(CPROVER_PREFIX "_start"))
   {
     const symbolt &entry_point_symbol=*maybe_symbol;
 
diff --git a/src/util/symbol_table.cpp b/src/util/symbol_table.cpp
index 0cf07f24683..ed8b67b1bb2 100644
--- a/src/util/symbol_table.cpp
+++ b/src/util/symbol_table.cpp
@@ -148,30 +148,6 @@ void symbol_tablet::show(std::ostream &out) const
     out << it->second;
 }
 
-/// Find a symbol in the symbol table for read-only access.
-/// \param identifier: The name of the symbol to look for
-/// \return an optional reference, set if found, unset otherwise.
-symbol_tablet::opt_const_symbol_reft symbol_tablet::lookup(
-  const irep_idt &identifier) const
-{
-  symbolst::const_iterator it=symbols.find(identifier);
-  if(it==symbols.end())
-    return opt_const_symbol_reft();
-  return std::ref(it->second);
-}
-
-/// Find a symbol in the symbol table for read-write access.
-/// \param identifier: The name of the symbol to look for
-/// \return an optional reference, set if found, unset otherwise.
-symbol_tablet::opt_symbol_reft symbol_tablet::get_writeable(
-  const irep_idt &identifier)
-{
-  symbolst::iterator it=internal_symbols.find(identifier);
-  if(it==symbols.end())
-    return opt_symbol_reft();
-  return std::ref(it->second);
-}
-
 /// Print the contents of the symbol table
 /// \param out: The ostream to direct output to
 /// \param symbol_table: The symbol table to print out
diff --git a/src/util/symbol_table.h b/src/util/symbol_table.h
index 4fb920a179d..42893a0882d 100644
--- a/src/util/symbol_table.h
+++ b/src/util/symbol_table.h
@@ -41,9 +41,6 @@ class symbol_tablet
 {
 public:
   typedef std::unordered_map<irep_idt, symbolt, irep_id_hash> symbolst;
-  typedef optionalt<std::reference_wrapper<const symbolt>>
-    opt_const_symbol_reft;
-  typedef optionalt<std::reference_wrapper<symbolt>> opt_symbol_reft;
 
 private:
   symbolst internal_symbols;
@@ -101,9 +98,29 @@ class symbol_tablet
     return symbols.find(name)!=symbols.end();
   }
 
-  opt_const_symbol_reft lookup(const irep_idt &identifier) const;
-
-  opt_symbol_reft get_writeable(const irep_idt &identifier);
+  /// Find a symbol in the symbol table for read-only access.
+  /// \param id: The name of the symbol to look for
+  /// \return an optional reference, set if found, nullptr otherwise.
+  const symbolt *lookup(const irep_idt &id) const { return lookup_impl(id); }
+
+  /// Find a symbol in the symbol table for read-write access.
+  /// \param id: The name of the symbol to look for
+  /// \return an optional reference, set if found, unset otherwise.
+  symbolt *get_writeable(const irep_idt &id) { return lookup_impl(id); }
+
+  /// Find a symbol in the symbol table for read-only access.
+  /// \param id: The name of the symbol to look for
+  /// \return A reference to the symbol
+  /// \throw `std::out_of_range` if no such symbol exists
+  const symbolt &lookup_ref(const irep_idt &id) const
+    { return internal_symbols.at(id); }
+
+  /// Find a symbol in the symbol table for read-write access.
+  /// \param id: The name of the symbol to look for
+  /// \return A reference to the symbol
+  /// \throw `std::out_of_range` if no such symbol exists
+  symbolt &get_writeable_ref(const irep_idt &id)
+    { return internal_symbols.at(id); }
 
   bool add(const symbolt &symbol);
 
@@ -130,6 +147,21 @@ class symbol_tablet
     internal_symbol_base_map.swap(other.internal_symbol_base_map);
     internal_symbol_module_map.swap(other.internal_symbol_module_map);
   }
+
+private:
+  const symbolt *lookup_impl(const irep_idt &id) const
+    { return lookup_impl(*this, id); }
+
+  symbolt *lookup_impl(const irep_idt &id)
+    { return lookup_impl(*this, id); }
+
+  template<typename T>
+  static auto lookup_impl(T &t, const irep_idt &id)
+    -> decltype(std::declval<T>().lookup_impl(id))
+  {
+    const auto it=t.internal_symbols.find(id);
+    return it==t.internal_symbols.end()?nullptr:&it->second;
+  }
 };
 
 std::ostream &operator << (
diff --git a/unit/java_bytecode/java_bytecode_parse_generics/parse_derived_generic_class.cpp b/unit/java_bytecode/java_bytecode_parse_generics/parse_derived_generic_class.cpp
index 1b2e6941bd7..0cab10c80e5 100644
--- a/unit/java_bytecode/java_bytecode_parse_generics/parse_derived_generic_class.cpp
+++ b/unit/java_bytecode/java_bytecode_parse_generics/parse_derived_generic_class.cpp
@@ -32,8 +32,7 @@ SCENARIO(
     std::string class_prefix="java::DerivedGeneric";
     REQUIRE(new_symbol_table.has_symbol(class_prefix));
 
-    const symbolt &derived_symbol=new_symbol_table.lookup(class_prefix).value
-      ().get();
+    const symbolt &derived_symbol=new_symbol_table.lookup_ref(class_prefix);
     REQUIRE(derived_symbol.is_type);
     const typet &derived_type=derived_symbol.type;
     REQUIRE(derived_type.id()==ID_struct);
diff --git a/unit/java_bytecode/java_bytecode_parse_generics/parse_generic_array_class.cpp b/unit/java_bytecode/java_bytecode_parse_generics/parse_generic_array_class.cpp
index 21665f7b523..6060c33c906 100644
--- a/unit/java_bytecode/java_bytecode_parse_generics/parse_generic_array_class.cpp
+++ b/unit/java_bytecode/java_bytecode_parse_generics/parse_generic_array_class.cpp
@@ -32,8 +32,7 @@ SCENARIO(
   REQUIRE(new_symbol_table.has_symbol(class_prefix));
 
   const struct_typet &type=to_struct_type(
-    new_symbol_table.lookup(class_prefix)
-      .value().get().type);
+    new_symbol_table.lookup_ref(class_prefix).type);
 
   THEN("There should be a component with name t")
   {
@@ -48,8 +47,7 @@ SCENARIO(
   THEN("The t component is a valid java array")
   {
     const struct_typet &subtype_type=to_struct_type(
-      new_symbol_table.lookup(subtype.get_identifier())
-        .value().get().type);
+      new_symbol_table.lookup_ref(subtype.get_identifier()).type);
     REQUIRE(is_valid_java_array(subtype_type));
   }