diff --git a/s390x/msa_x4/gcm-hash.asm b/s390x/msa_x4/gcm-hash.asm
index 73a50824a0abab0b23c6f49bd60011ac9dcfa53c..3bbc8a63215870a58104cb9bbd9a2034a4d9aaff 100644
--- a/s390x/msa_x4/gcm-hash.asm
+++ b/s390x/msa_x4/gcm-hash.asm
@@ -92,6 +92,7 @@ PROLOGUE(_nettle_gcm_hash)
     brc            1,3b                          C safely branch back in case of partial completion
 4:
     mvc            0(16,%r6),0(%r1)              C store x
+    xc             16(16,%r1),16(%r1)            C wipe hash subkey from stack
     FREE_STACK(PB_SIZE+16)
     lgdr           %r6,%f0                       C restore general register 6
     br             RA