diff --git a/src/pkcs11/mechanism.c b/src/pkcs11/mechanism.c
index 122dee7b..99b9f912 100644
--- a/src/pkcs11/mechanism.c
+++ b/src/pkcs11/mechanism.c
@@ -80,10 +80,13 @@ sc_pkcs11_get_mechanism_list(struct sc_pkcs11_card *p11card,
 	unsigned int n, count = 0;
 	int rv;
 
+	if (!pulCount)
+		return CKR_ARGUMENTS_BAD;
+
 	for (n = 0; n < p11card->nmechanisms; n++) {
 		if (!(mt = p11card->mechanisms[n]))
 			continue;
-		if (count < *pulCount && pList)
+		if (pList && count < *pulCount)
 			pList[count] = mt->mech;
 		count++;
 	}