Index: src/ResolvExpr/TypeEnvironment.cc
===================================================================
--- src/ResolvExpr/TypeEnvironment.cc	(revision 2c57025b9dec0a2c5dae7c32ad6e1ac3ccf8f76e)
+++ src/ResolvExpr/TypeEnvironment.cc	(revision fc638d2176b72a88b406e73af7f7f9e548ae05f7)
@@ -32,5 +32,5 @@
 	//
 	// I've seen a TU go from 54 minutes to 1 minute 34 seconds with the addition of this comparator.
-	bool AssertCompare::operator()( DeclarationWithType * d1, DeclarationWithType * d2 ) {
+	bool AssertCompare::operator()( DeclarationWithType * d1, DeclarationWithType * d2 ) const {
 			// Objects are always less than functions
 			if ( ObjectDecl * objectDecl1 = dynamic_cast< ObjectDecl * >( d1 ) ) {
Index: src/ResolvExpr/TypeEnvironment.h
===================================================================
--- src/ResolvExpr/TypeEnvironment.h	(revision 2c57025b9dec0a2c5dae7c32ad6e1ac3ccf8f76e)
+++ src/ResolvExpr/TypeEnvironment.h	(revision fc638d2176b72a88b406e73af7f7f9e548ae05f7)
@@ -29,5 +29,5 @@
 namespace ResolvExpr {
 	struct AssertCompare {
-		bool operator()( DeclarationWithType * d1, DeclarationWithType * d2 );
+		bool operator()( DeclarationWithType * d1, DeclarationWithType * d2 ) const;
 	};
 	typedef std::map< DeclarationWithType*, bool, AssertCompare > AssertionSet;