diff --git a/crypto/mem_clr.c b/crypto/mem_clr.c
index 1a06636d0..5c03dff79 100644
--- a/crypto/mem_clr.c
+++ b/crypto/mem_clr.c
@@ -60,6 +60,7 @@
 #include <string.h>
 #include <openssl/crypto.h>
 
+extern unsigned char cleanse_ctr;
 unsigned char cleanse_ctr = 0;
 
 void OPENSSL_cleanse(void *ptr, size_t len)