diff --git a/src/aclocal.m4 b/src/aclocal.m4
index 0865c39b538485b2e328049934dfe26b21674bf2..e6f052ee8be0375da144aac67356eb475e443411 100644
--- a/src/aclocal.m4
+++ b/src/aclocal.m4
@@ -782,7 +782,7 @@ int main() {
   fclose(f);
   f = fopen("conftestval","w");
   if (f == NULL) exit(1);
-  fprintf(f, output);
+  fputs(output, f);
   fclose(f);
   exit(0);
 }