Index: src/SynTree/GcTracer.h
===================================================================
--- src/SynTree/GcTracer.h	(revision 9f2012f92e024a65ddf3856c93f9664f8b327a1c)
+++ src/SynTree/GcTracer.h	(revision 09a1ae65b16a0d81b5e42e0db3d06d4ae0941448)
@@ -34,4 +34,6 @@
 	GcTracer( const GC& gc ) : gc(gc) {}
 
+	// mark node and children
+
 	void previsit( BaseSyntaxNode * node ) {
 		// skip tree if already seen
@@ -45,6 +47,13 @@
 	}
 
+	// add visits left out by PassVisitor
+
 	void postvisit( Expression* expr ) {
 		maybeAccept( expr->env, *visitor );
+	}
+
+	void postvisit( UntypedExpr* expr ) {
+		postvisit( static_cast<Expression*>(expr) );
+		maybeAccept( expr->function, *visitor );
 	}