Index: src/ResolvExpr/AlternativeFinder.cc
===================================================================
--- src/ResolvExpr/AlternativeFinder.cc	(revision 3d2ae8d640c6d34580f0205a61f382a75affe92a)
+++ src/ResolvExpr/AlternativeFinder.cc	(revision 1f81d61c0a8d53662c51e645fbbb076881fd849c)
@@ -1292,4 +1292,6 @@
 			AssertionSet needAssertions, haveAssertions;
 			OpenVarSet openVars;
+
+			alt.env.extractOpenVars( openVars );
 
 			// It's possible that a cast can throw away some values in a multiply-valued expression.  (An example is a