diff --git a/sys/crypto/siphash/siphash.c b/sys/crypto/siphash/siphash.c
index b1065d7e..efb7bd3a 100644
--- a/sys/crypto/siphash/siphash.c
+++ b/sys/crypto/siphash/siphash.c
@@ -81,6 +81,8 @@ SipHash_SetKey(SIPHASH_CTX *ctx, const uint8_t key[static SIPHASH_KEY_LENGTH])
 	ctx->v[2] ^= k[0];
 	ctx->v[3] ^= k[1];
 
+	explicit_bzero(k, sizeof(k));
+
 	ctx->initialized = 2;
 }