diff --git a/src/ansi-c/CMakeLists.txt b/src/ansi-c/CMakeLists.txt
index be4d003342e..43c38d3999f 100644
--- a/src/ansi-c/CMakeLists.txt
+++ b/src/ansi-c/CMakeLists.txt
@@ -58,6 +58,7 @@ add_custom_target(library_check
 
 make_inc(arm_builtin_headers)
 make_inc(clang_builtin_headers)
+make_inc(cprover_builtin_headers)
 make_inc(cw_builtin_headers)
 make_inc(gcc_builtin_headers_alpha)
 make_inc(gcc_builtin_headers_arm)
@@ -74,11 +75,13 @@ make_inc(gcc_builtin_headers_power)
 make_inc(gcc_builtin_headers_tm)
 make_inc(gcc_builtin_headers_types)
 make_inc(gcc_builtin_headers_ubsan)
+make_inc(windows_builtin_headers)
 
 set(extra_dependencies
     ${CMAKE_CURRENT_BINARY_DIR}/arm_builtin_headers.inc
     ${CMAKE_CURRENT_BINARY_DIR}/clang_builtin_headers.inc
     ${CMAKE_CURRENT_BINARY_DIR}/cprover_library.inc
+    ${CMAKE_CURRENT_BINARY_DIR}/cprover_builtin_headers.inc
     ${CMAKE_CURRENT_BINARY_DIR}/cw_builtin_headers.inc
     ${CMAKE_CURRENT_BINARY_DIR}/gcc_builtin_headers_alpha.inc
     ${CMAKE_CURRENT_BINARY_DIR}/gcc_builtin_headers_arm.inc
@@ -95,6 +98,7 @@ set(extra_dependencies
     ${CMAKE_CURRENT_BINARY_DIR}/gcc_builtin_headers_tm.inc
     ${CMAKE_CURRENT_BINARY_DIR}/gcc_builtin_headers_types.inc
     ${CMAKE_CURRENT_BINARY_DIR}/gcc_builtin_headers_ubsan.inc
+    ${CMAKE_CURRENT_BINARY_DIR}/windows_builtin_headers.inc
     ${CMAKE_CURRENT_BINARY_DIR}/library-check.stamp
 )
 
diff --git a/src/ansi-c/Makefile b/src/ansi-c/Makefile
index 97519b2a4df..ada37c47f0c 100644
--- a/src/ansi-c/Makefile
+++ b/src/ansi-c/Makefile
@@ -47,6 +47,7 @@ include ../common
 BUILTIN_FILES = \
   arm_builtin_headers.inc \
   clang_builtin_headers.inc \
+  cprover_builtin_headers.inc \
   cw_builtin_headers.inc \
   gcc_builtin_headers_alpha.inc \
   gcc_builtin_headers_arm.inc \
@@ -62,7 +63,8 @@ BUILTIN_FILES = \
   gcc_builtin_headers_power.inc \
   gcc_builtin_headers_tm.inc \
   gcc_builtin_headers_types.inc \
-  gcc_builtin_headers_ubsan.inc
+  gcc_builtin_headers_ubsan.inc \
+  windows_builtin_headers.inc
 
 CLEANFILES = ansi-c$(LIBEXT) \
   ansi_c_y.tab.h ansi_c_y.tab.cpp ansi_c_lex.yy.cpp ansi_c_y.tab.cpp.output \
diff --git a/src/ansi-c/ansi_c_internal_additions.cpp b/src/ansi-c/ansi_c_internal_additions.cpp
index abcf362a943..845e2197e84 100644
--- a/src/ansi-c/ansi_c_internal_additions.cpp
+++ b/src/ansi-c/ansi_c_internal_additions.cpp
@@ -94,9 +94,15 @@ const char clang_builtin_headers[]=
 #include "clang_builtin_headers.inc"
 ; // NOLINT(whitespace/semicolon)
 
+const char cprover_builtin_headers[]=
+"# 1 \"cprover_builtin_headers.h\"\n"
+#include "cprover_builtin_headers.inc"
+; // NOLINT(whitespace/semicolon)
+
 const char windows_builtin_headers[]=
-  "int __noop();\n"
-  "int __assume(int);\n";
+"# 1 \"windows_builtin_headers.h\"\n"
+#include "windows_builtin_headers.inc"
+; // NOLINT(whitespace/semicolon)
 
 static std::string architecture_string(const std::string &value, const char *s)
 {
@@ -114,68 +120,28 @@ static std::string architecture_string(int value, const char *s)
 
 void ansi_c_internal_additions(std::string &code)
 {
+  // do the built-in types and variables
   code+=
     "# 1 \"<built-in-additions>\"\n"
     "typedef __typeof__(sizeof(int)) __CPROVER_size_t;\n"
-    "void __CPROVER_assume(__CPROVER_bool assumption);\n"
-    "void __VERIFIER_assume(__CPROVER_bool assumption);\n"
-    // NOLINTNEXTLINE(whitespace/line_length)
-    "void __CPROVER_assert(__CPROVER_bool assertion, const char *description);\n"
-    // NOLINTNEXTLINE(whitespace/line_length)
-    "void __CPROVER_precondition(__CPROVER_bool precondition, const char *description);\n"
-    "void __CPROVER_havoc_object(void *);\n"
-    "__CPROVER_bool __CPROVER_equal();\n"
-    "__CPROVER_bool __CPROVER_same_object(const void *, const void *);\n"
-    "__CPROVER_bool __CPROVER_invalid_pointer(const void *);\n"
-    "__CPROVER_bool __CPROVER_is_zero_string(const void *);\n"
-    "__CPROVER_size_t __CPROVER_zero_string_length(const void *);\n"
-    "__CPROVER_size_t __CPROVER_buffer_size(const void *);\n"
-
-    "__CPROVER_bool __CPROVER_get_flag(const void *, const char *);\n"
-    "void __CPROVER_set_must(const void *, const char *);\n"
-    "void __CPROVER_clear_must(const void *, const char *);\n"
-    "void __CPROVER_set_may(const void *, const char *);\n"
-    "void __CPROVER_clear_may(const void *, const char *);\n"
-    "void __CPROVER_cleanup(const void *, const void *);\n"
-    "__CPROVER_bool __CPROVER_get_must(const void *, const char *);\n"
-    "__CPROVER_bool __CPROVER_get_may(const void *, const char *);\n"
-
     "const unsigned __CPROVER_constant_infinity_uint;\n"
     "typedef void __CPROVER_integer;\n"
     "typedef void __CPROVER_rational;\n"
-    "void __CPROVER_initialize(void);\n"
-    "void __CPROVER_input(const char *id, ...);\n"
-    "void __CPROVER_output(const char *id, ...);\n"
-    "void __CPROVER_cover(__CPROVER_bool condition);\n"
-
-    // concurrency-related
-    "void __CPROVER_atomic_begin();\n"
-    "void __CPROVER_atomic_end();\n"
-    "void __CPROVER_fence(const char *kind, ...);\n"
     "__CPROVER_thread_local unsigned long __CPROVER_thread_id=0;\n"
     // NOLINTNEXTLINE(whitespace/line_length)
     "__CPROVER_bool __CPROVER_threads_exited[__CPROVER_constant_infinity_uint];\n"
     "unsigned long __CPROVER_next_thread_id=0;\n"
-
-    // traces
-    "void CBMC_trace(int lvl, const char *event, ...);\n"
-
-    // pointers
-    "unsigned __CPROVER_POINTER_OBJECT(const void *p);\n"
-    "signed __CPROVER_POINTER_OFFSET(const void *p);\n"
-    "__CPROVER_bool __CPROVER_DYNAMIC_OBJECT(const void *p);\n"
-    "extern unsigned char __CPROVER_memory[__CPROVER_constant_infinity_uint];\n"
     // NOLINTNEXTLINE(whitespace/line_length)
-    "void __CPROVER_allocated_memory(__CPROVER_size_t address, __CPROVER_size_t extent);\n"
+    "extern unsigned char __CPROVER_memory[__CPROVER_constant_infinity_uint];\n"
 
     // malloc
-    "void *__CPROVER_allocate(__CPROVER_size_t size, __CPROVER_bool zero);\n"
     "const void *__CPROVER_deallocated=0;\n"
     "const void *__CPROVER_dead_object=0;\n"
     "const void *__CPROVER_malloc_object=0;\n"
     "__CPROVER_size_t __CPROVER_malloc_size;\n"
     "__CPROVER_bool __CPROVER_malloc_is_new_array=0;\n" // for C++
     "const void *__CPROVER_memory_leak=0;\n"
+    "void *__CPROVER_allocate(__CPROVER_size_t size, __CPROVER_bool zero);\n"
 
     // this is ANSI-C
     // NOLINTNEXTLINE(whitespace/line_length)
@@ -188,63 +154,8 @@ void ansi_c_internal_additions(std::string &code)
     "extern __CPROVER_thread_local const char __PRETTY_FUNCTION__[__CPROVER_constant_infinity_uint];\n"
 
     // float stuff
-    "__CPROVER_bool __CPROVER_isnanf(float f);\n"
-    "__CPROVER_bool __CPROVER_isnand(double f);\n"
-    "__CPROVER_bool __CPROVER_isnanld(long double f);\n"
-    "__CPROVER_bool __CPROVER_isfinitef(float f);\n"
-    "__CPROVER_bool __CPROVER_isfinited(double f);\n"
-    "__CPROVER_bool __CPROVER_isfiniteld(long double f);\n"
-    "__CPROVER_bool __CPROVER_isinff(float f);\n"
-    "__CPROVER_bool __CPROVER_isinfd(double f);\n"
-    "__CPROVER_bool __CPROVER_isinfld(long double f);\n"
-    "__CPROVER_bool __CPROVER_isnormalf(float f);\n"
-    "__CPROVER_bool __CPROVER_isnormald(double f);\n"
-    "__CPROVER_bool __CPROVER_isnormalld(long double f);\n"
-    "__CPROVER_bool __CPROVER_signf(float f);\n"
-    "__CPROVER_bool __CPROVER_signd(double f);\n"
-    "__CPROVER_bool __CPROVER_signld(long double f);\n"
-    "double __CPROVER_inf(void);\n"
-    "float __CPROVER_inff(void);\n"
-    "long double __CPROVER_infl(void);\n"
     "int __CPROVER_thread_local __CPROVER_rounding_mode="+
       std::to_string(config.ansi_c.rounding_mode)+";\n"
-    "int __CPROVER_isgreaterf(float f, float g);\n"
-    "int __CPROVER_isgreaterd(double f, double g);\n"
-    "int __CPROVER_isgreaterequalf(float f, float g);\n"
-    "int __CPROVER_isgreaterequald(double f, double g);\n"
-    "int __CPROVER_islessf(float f, float g);\n"
-    "int __CPROVER_islessd(double f, double g);\n"
-    "int __CPROVER_islessequalf(float f, float g);\n"
-    "int __CPROVER_islessequald(double f, double g);\n"
-    "int __CPROVER_islessgreaterf(float f, float g);\n"
-    "int __CPROVER_islessgreaterd(double f, double g);\n"
-    "int __CPROVER_isunorderedf(float f, float g);\n"
-    "int __CPROVER_isunorderedd(double f, double g);\n"
-
-    // absolute value
-    "int __CPROVER_abs(int x);\n"
-    "long int __CPROVER_labs(long int x);\n"
-    "long int __CPROVER_llabs(long long int x);\n"
-    "double __CPROVER_fabs(double x);\n"
-    "long double __CPROVER_fabsl(long double x);\n"
-    "float __CPROVER_fabsf(float x);\n"
-
-    // arrays
-    // NOLINTNEXTLINE(whitespace/line_length)
-    "__CPROVER_bool __CPROVER_array_equal(const void *array1, const void *array2);\n"
-    // overwrite all of *dest (possibly using nondet values), even
-    // if *src is smaller
-    "void __CPROVER_array_copy(const void *dest, const void *src);\n"
-    // replace at most size-of-*src bytes in *dest
-    "void __CPROVER_array_replace(const void *dest, const void *src);\n"
-    "void __CPROVER_array_set(const void *dest, ...);\n"
-
-    // k-induction
-    "void __CPROVER_k_induction_hint(unsigned min, unsigned max, "
-      "unsigned step, unsigned loop_free);\n"
-
-    // format string-related
-    "int __CPROVER_scanf(const char *, ...);\n"
 
     // pipes, write, read, close
     "struct __CPROVER_pipet {\n"
@@ -258,7 +169,10 @@ void ansi_c_internal_additions(std::string &code)
     // offset to make sure we don't collide with other fds
     "extern const int __CPROVER_pipe_offset;\n"
     "unsigned __CPROVER_pipe_count=0;\n"
-
+    "\n"
+    // This function needs to be declared, or otherwise can't be called
+    // by the entry-point construction.
+    "void __CPROVER_initialize(void);\n"
     "\n";
 
   // GCC junk stuff, also for CLANG and ARM
diff --git a/src/ansi-c/ansi_c_internal_additions.h b/src/ansi-c/ansi_c_internal_additions.h
index 10e7c8e144d..20801df6ae2 100644
--- a/src/ansi-c/ansi_c_internal_additions.h
+++ b/src/ansi-c/ansi_c_internal_additions.h
@@ -16,6 +16,7 @@ void ansi_c_internal_additions(std::string &code);
 void ansi_c_architecture_strings(std::string &code);
 
 extern const char clang_builtin_headers[];
+extern const char cprover_builtin_headers[];
 extern const char gcc_builtin_headers_types[];
 extern const char gcc_builtin_headers_generic[];
 extern const char gcc_builtin_headers_math[];
diff --git a/src/ansi-c/builtin_factory.cpp b/src/ansi-c/builtin_factory.cpp
index cd839a46223..a92269a754c 100644
--- a/src/ansi-c/builtin_factory.cpp
+++ b/src/ansi-c/builtin_factory.cpp
@@ -108,6 +108,10 @@ bool builtin_factory(
   ansi_c_internal_additions(code);
   s << code;
 
+  // our own extensions
+  if(find_pattern(pattern, cprover_builtin_headers, s))
+    return convert(identifier, s, symbol_table, mh);
+
   // this is Visual C/C++ only
   if(config.ansi_c.os==configt::ansi_ct::ost::OS_WIN)
   {
diff --git a/src/ansi-c/cprover_builtin_headers.h b/src/ansi-c/cprover_builtin_headers.h
new file mode 100644
index 00000000000..196e6a8f21e
--- /dev/null
+++ b/src/ansi-c/cprover_builtin_headers.h
@@ -0,0 +1,96 @@
+void __CPROVER_assume(__CPROVER_bool assumption);
+void __VERIFIER_assume(__CPROVER_bool assumption);
+void __CPROVER_assert(__CPROVER_bool assertion, const char *description);
+void __CPROVER_precondition(__CPROVER_bool precondition, const char *description);
+void __CPROVER_havoc_object(void *);
+__CPROVER_bool __CPROVER_equal();
+__CPROVER_bool __CPROVER_same_object(const void *, const void *);
+__CPROVER_bool __CPROVER_invalid_pointer(const void *);
+__CPROVER_bool __CPROVER_is_zero_string(const void *);
+__CPROVER_size_t __CPROVER_zero_string_length(const void *);
+__CPROVER_size_t __CPROVER_buffer_size(const void *);
+
+// bitvector analysis
+__CPROVER_bool __CPROVER_get_flag(const void *, const char *);
+void __CPROVER_set_must(const void *, const char *);
+void __CPROVER_clear_must(const void *, const char *);
+void __CPROVER_set_may(const void *, const char *);
+void __CPROVER_clear_may(const void *, const char *);
+void __CPROVER_cleanup(const void *, const void *);
+__CPROVER_bool __CPROVER_get_must(const void *, const char *);
+__CPROVER_bool __CPROVER_get_may(const void *, const char *);
+
+void __CPROVER_input(const char *id, ...);
+void __CPROVER_output(const char *id, ...);
+void __CPROVER_cover(__CPROVER_bool condition);
+
+// concurrency-related
+void __CPROVER_atomic_begin();
+void __CPROVER_atomic_end();
+void __CPROVER_fence(const char *kind, ...);
+
+// traces
+void CBMC_trace(int lvl, const char *event, ...);
+
+// pointers
+unsigned __CPROVER_POINTER_OBJECT(const void *p);
+signed __CPROVER_POINTER_OFFSET(const void *p);
+__CPROVER_bool __CPROVER_DYNAMIC_OBJECT(const void *p);
+void __CPROVER_allocated_memory(__CPROVER_size_t address, __CPROVER_size_t extent);
+
+// float stuff
+__CPROVER_bool __CPROVER_isnanf(float f);
+__CPROVER_bool __CPROVER_isnand(double f);
+__CPROVER_bool __CPROVER_isnanld(long double f);
+__CPROVER_bool __CPROVER_isfinitef(float f);
+__CPROVER_bool __CPROVER_isfinited(double f);
+__CPROVER_bool __CPROVER_isfiniteld(long double f);
+__CPROVER_bool __CPROVER_isinff(float f);
+__CPROVER_bool __CPROVER_isinfd(double f);
+__CPROVER_bool __CPROVER_isinfld(long double f);
+__CPROVER_bool __CPROVER_isnormalf(float f);
+__CPROVER_bool __CPROVER_isnormald(double f);
+__CPROVER_bool __CPROVER_isnormalld(long double f);
+__CPROVER_bool __CPROVER_signf(float f);
+__CPROVER_bool __CPROVER_signd(double f);
+__CPROVER_bool __CPROVER_signld(long double f);
+double __CPROVER_inf(void);
+float __CPROVER_inff(void);
+long double __CPROVER_infl(void);
+int __CPROVER_isgreaterf(float f, float g);
+int __CPROVER_isgreaterd(double f, double g);
+int __CPROVER_isgreaterequalf(float f, float g);
+int __CPROVER_isgreaterequald(double f, double g);
+int __CPROVER_islessf(float f, float g);
+int __CPROVER_islessd(double f, double g);
+int __CPROVER_islessequalf(float f, float g);
+int __CPROVER_islessequald(double f, double g);
+int __CPROVER_islessgreaterf(float f, float g);
+int __CPROVER_islessgreaterd(double f, double g);
+int __CPROVER_isunorderedf(float f, float g);
+int __CPROVER_isunorderedd(double f, double g);
+
+// absolute value
+int __CPROVER_abs(int x);
+long int __CPROVER_labs(long int x);
+long int __CPROVER_llabs(long long int x);
+double __CPROVER_fabs(double x);
+long double __CPROVER_fabsl(long double x);
+float __CPROVER_fabsf(float x);
+
+// arrays
+__CPROVER_bool __CPROVER_array_equal(const void *array1, const void *array2);
+// overwrite all of *dest (possibly using nondet values), even
+// if *src is smaller
+void __CPROVER_array_copy(const void *dest, const void *src);
+// replace at most size-of-*src bytes in *dest
+void __CPROVER_array_replace(const void *dest, const void *src);
+void __CPROVER_array_set(const void *dest, ...);
+
+// k-induction
+void __CPROVER_k_induction_hint(unsigned min, unsigned max, 
+  unsigned step, unsigned loop_free);
+
+// format string-related
+int __CPROVER_scanf(const char *, ...);
+
diff --git a/src/ansi-c/windows_builtin_headers.h b/src/ansi-c/windows_builtin_headers.h
new file mode 100644
index 00000000000..cf162f8db96
--- /dev/null
+++ b/src/ansi-c/windows_builtin_headers.h
@@ -0,0 +1,2 @@
+int __noop();
+int __assume(int);