diff --git a/include/clang/StaticAnalyzer/PathSensitive/ExplodedGraph.h b/include/clang/StaticAnalyzer/PathSensitive/ExplodedGraph.h
index 3a7a991..853d3c5 100644
--- a/include/clang/StaticAnalyzer/PathSensitive/ExplodedGraph.h
+++ b/include/clang/StaticAnalyzer/PathSensitive/ExplodedGraph.h
@@ -47,6 +47,9 @@
 // on top of these classes.
 //===----------------------------------------------------------------------===//
 
+// ExplodedNode is not constified all over the engine because we need to add
+// successors to it at any time after creating it.
+
 class ExplodedNode : public llvm::FoldingSetNode {
   friend class ExplodedGraph;
   friend class CoreEngine;