diff --git a/configure b/configure
index 861a67d0..b043dab0 100755
--- a/configure
+++ b/configure
@@ -390,7 +390,8 @@ else
 #define _GNU_SOURCE
 #include <stdio.h>
 int main(void) {
-	vasprintf(NULL, NULL, NULL);
+	va_list ap;
+	vasprintf(NULL, NULL, ap);
 	return 0;
 }
 EOF