diff --git a/include/llvm/Analysis/DSGraph.h b/include/llvm/Analysis/DSGraph.h
index 0126e2d44f8..c5e9396a16b 100644
--- a/include/llvm/Analysis/DSGraph.h
+++ b/include/llvm/Analysis/DSGraph.h
@@ -53,7 +53,10 @@ public:
   ~DSGraph();
 
   bool hasFunction() const { return Func != 0; }
-  Function &getFunction() const { return *Func; }
+  Function &getFunction() const {
+    assert(hasFunction() && "Cannot call getFunction on graph without a fn!");
+    return *Func;
+  }
 
   DSGraph *getGlobalsGraph() const { return GlobalsGraph; }
   void setGlobalsGraph(DSGraph *G) { GlobalsGraph = G; }
diff --git a/include/llvm/Analysis/DataStructure/DSGraph.h b/include/llvm/Analysis/DataStructure/DSGraph.h
index 0126e2d44f8..c5e9396a16b 100644
--- a/include/llvm/Analysis/DataStructure/DSGraph.h
+++ b/include/llvm/Analysis/DataStructure/DSGraph.h
@@ -53,7 +53,10 @@ public:
   ~DSGraph();
 
   bool hasFunction() const { return Func != 0; }
-  Function &getFunction() const { return *Func; }
+  Function &getFunction() const {
+    assert(hasFunction() && "Cannot call getFunction on graph without a fn!");
+    return *Func;
+  }
 
   DSGraph *getGlobalsGraph() const { return GlobalsGraph; }
   void setGlobalsGraph(DSGraph *G) { GlobalsGraph = G; }
diff --git a/lib/Analysis/DataStructure/DataStructure.cpp b/lib/Analysis/DataStructure/DataStructure.cpp
index 80c64d126c6..badc9c08013 100644
--- a/lib/Analysis/DataStructure/DataStructure.cpp
+++ b/lib/Analysis/DataStructure/DataStructure.cpp
@@ -1029,6 +1029,7 @@ void DSGraph::removeDeadNodes(unsigned Flags) {
     if (AuxFCallsAlive[i])
       AuxFunctionCalls[CurIdx++].swap(AuxFunctionCalls[i]);
   if (!(Flags & DSGraph::RemoveUnreachableGlobals)) {
+    assert(GlobalsGraph && "No globals graph available??");
     // Move the unreachable call nodes to the globals graph...
     GlobalsGraph->AuxFunctionCalls.insert(GlobalsGraph->AuxFunctionCalls.end(),
                                           AuxFunctionCalls.begin()+CurIdx,