Accept NULL in *_free.
diff --git a/crypto/err/err.c b/crypto/err/err.c
index 5cf6218..39c997a 100644
--- a/crypto/err/err.c
+++ b/crypto/err/err.c
@@ -175,6 +175,9 @@
 	{
 	int i;
 
+	if(s == NULL)
+	    return;
+
 	for (i=0; i<ERR_NUM_ERRORS; i++)
 		{
 		err_clear_data(s,i);