Index: src/ResolvExpr/AlternativeFinder.cc
===================================================================
--- src/ResolvExpr/AlternativeFinder.cc	(revision 5f5083ecd08695483327d194d9c4c0c2df735fb7)
+++ src/ResolvExpr/AlternativeFinder.cc	(revision 668e971a4b0566f4b96f071a18a0a01df07df822)
@@ -1004,5 +1004,5 @@
 					AssertionSet needAssertions, haveAssertions;
 					Alternative newAlt( 0, third->env, first->cost + second->cost + third->cost );
-					Type* commonType;
+					Type* commonType = nullptr;
 					if ( unify( second->expr->get_result(), third->expr->get_result(), newAlt.env, needAssertions, haveAssertions, openVars, indexer, commonType ) ) {
 						ConditionalExpr *newExpr = new ConditionalExpr( first->expr->clone(), second->expr->clone(), third->expr->clone() );