diff --git a/lib/config-win32.h b/lib/config-win32.h
index 6d60735a763d6c896a15085e9e3d57ef66e9a58d..cb6017ae067d9e70fb02afd86912a32df098a25b 100644
--- a/lib/config-win32.h
+++ b/lib/config-win32.h
@@ -91,6 +91,11 @@
 /* Define if you have the strstr function.  */
 #define HAVE_STRSTR 1
 
+/* Define if you have the strtoll function.  */
+#ifdef MINGW32
+#define HAVE_STRTOLL 1
+#endif
+
 /* Define if you have the tcgetattr function.  */
 /*#define HAVE_TCGETATTR 1*/