diff --git a/lib/polarsslthreadlock.c b/lib/polarsslthreadlock.c
index acef2fea01..46d17784fd 100755
--- a/lib/polarsslthreadlock.c
+++ b/lib/polarsslthreadlock.c
@@ -41,6 +41,10 @@
 
 #include "polarsslthreadlock.h"
 
+#include "curl_memory.h"
+/* The last #include file should be: */
+#include "memdebug.h"
+
 /* number of thread locks */
 #define NUMT                    2