diff --git a/src/ast/ast.cpp b/src/ast/ast.cpp
index 84f2e9c1b..bff812ec4 100644
--- a/src/ast/ast.cpp
+++ b/src/ast/ast.cpp
@@ -1674,7 +1674,7 @@ bool ast_manager::slow_not_contains(ast const * n) {
 }
 #endif
 
-#if 0
+#if 1
 static unsigned s_count = 0;
 
 static void track_id(ast_manager& m, ast* n, unsigned id) {