diff --git a/tools/gen-expr/Makefile b/tools/gen-expr/Makefile
index ed8e85707dbe35f757433e9baae57a1618f7c417..d04eb38046b55a482b8780c0d8db640b33f57b6f 100644
--- a/tools/gen-expr/Makefile
+++ b/tools/gen-expr/Makefile
@@ -5,4 +5,4 @@ $(APP): gen-expr.c
 
 .PHONY: clean
 clean:
-	-rm $(APP) .code.c .expr 2> /dev/null
+	-rm $(APP) 2> /dev/null
diff --git a/tools/gen-expr/gen-expr.c b/tools/gen-expr/gen-expr.c
index a94ff2411e969c393b4f09d20359498c7a46473e..4d3272d616108a1e1c6422396a43fd63f4305f5c 100644
--- a/tools/gen-expr/gen-expr.c
+++ b/tools/gen-expr/gen-expr.c
@@ -97,12 +97,15 @@ int main(int argc, char *argv[]) {
 
     sprintf(code_buf, code_format, buf);
 
-    FILE *fp = fopen(".code.c", "w");
+    FILE *fp = fopen("/tmp/.code.c", "w");
     assert(fp != NULL);
     fputs(code_buf, fp);
     fclose(fp);
 
-    fp = popen("gcc .code.c -Wall -Werror -o .expr && ./.expr", "r");
+    int ret = system("gcc /tmp/.code.c -o /tmp/.expr");
+    if (ret != 0) continue;
+
+    fp = popen("/tmp/.expr", "r");
     assert(fp != NULL);
     int result;
     fscanf(fp, "%d", &result);