diff --git a/regression/goto-instrument/dependence-graph1/main.c b/regression/goto-instrument/dependence-graph1/main.c
new file mode 100644
index 00000000000..e7b639d2070
--- /dev/null
+++ b/regression/goto-instrument/dependence-graph1/main.c
@@ -0,0 +1,18 @@
+
+int x;
+
+void func()
+{
+  int r;
+
+  r = x;
+}
+
+int main()
+{
+  x = 1;
+  func();
+
+  return 0;
+}
+
diff --git a/regression/goto-instrument/dependence-graph1/test.desc b/regression/goto-instrument/dependence-graph1/test.desc
new file mode 100644
index 00000000000..caef399aa9c
--- /dev/null
+++ b/regression/goto-instrument/dependence-graph1/test.desc
@@ -0,0 +1,7 @@
+CORE
+main.c
+--show-dependence-graph
+^EXIT=0$
+^SIGNAL=0$
+--
+^warning: ignoring
diff --git a/src/analyses/ai.cpp b/src/analyses/ai.cpp
index 552649d6009..4bc490a726b 100644
--- a/src/analyses/ai.cpp
+++ b/src/analyses/ai.cpp
@@ -499,10 +499,11 @@ void ai_baset::sequential_fixedpoint(
   const goto_functionst &goto_functions,
   const namespacet &ns)
 {
-  // do each function at least once
+  goto_functionst::function_mapt::const_iterator
+    f_it=goto_functions.function_map.find(goto_functions.entry_point());
 
-  forall_goto_functions(it, goto_functions)
-    fixedpoint(it->second.body, goto_functions, ns);
+  if(f_it!=goto_functions.function_map.end())
+    fixedpoint(f_it->second.body, goto_functions, ns);
 }
 
 /*******************************************************************\
diff --git a/src/analyses/dependence_graph.h b/src/analyses/dependence_graph.h
index 15c0828fef6..07bf28baa1b 100644
--- a/src/analyses/dependence_graph.h
+++ b/src/analyses/dependence_graph.h
@@ -94,14 +94,20 @@ class dep_graph_domaint:public ai_domain_baset
 
   void make_top() final override
   {
+    assert(node_id!=std::numeric_limits<node_indext>::max());
+
     has_values=tvt(true);
-    node_id=std::numeric_limits<node_indext>::max();
+    control_deps.clear();
+    data_deps.clear();
   }
 
   void make_bottom() final override
   {
+    assert(node_id!=std::numeric_limits<node_indext>::max());
+
     has_values=tvt(false);
-    node_id=std::numeric_limits<node_indext>::max();
+    control_deps.clear();
+    data_deps.clear();
   }
 
   void make_entry() final override
@@ -161,6 +167,7 @@ class dependence_grapht:
 
   void initialize(const goto_programt &goto_program)
   {
+    ait<dep_graph_domaint>::initialize(goto_program);
     post_dominators(goto_program);
   }