diff --git a/sys/crypto/skipjack.c b/sys/crypto/skipjack.c
index fea74652d8..610163c320 100644
--- a/sys/crypto/skipjack.c
+++ b/sys/crypto/skipjack.c
@@ -224,6 +224,8 @@ int skipjack_encrypt(cipher_context_t *context, uint8_t *plainBlock,
     s2cM(w3, cipherBlock);
     cipherBlock += 2;
     s2cM(w4, cipherBlock);
+    /* cppcheck: may introduce timing bias if left out */
+    /* cppcheck-suppress uselessAssignmentPtrArg */
     cipherBlock += 2;
 
     return 1;