diff --git a/crypto/aes/asm/aes-s390x.pl b/crypto/aes/asm/aes-s390x.pl
index 6ee2097a151674ac9651429d0883046a596ffc77..4b27afd92fc479773abd64e875901cfcb506242c 100644
--- a/crypto/aes/asm/aes-s390x.pl
+++ b/crypto/aes/asm/aes-s390x.pl
@@ -35,11 +35,11 @@
 #
 # Add support for hardware AES192/256 and reschedule instructions to
 # minimize/avoid Address Generation Interlock hazard and to favour
-# dual-issue z10 pipeline. This gave ~25% improvement on z10. The gain
-# should be larger on earlier CPUs, because being dual-issue z10 makes
-# it improssible to eliminate the interlock condition, critial path is
-# not long enough. Yet z10 spends ~24 cycles per byte processed with
-# 128-bit key.
+# dual-issue z10 pipeline. This gave ~25% improvement on z10 and
+# almost 50% on z9. The gain is smaller on z10, because being dual-
+# issue z10 makes it improssible to eliminate the interlock condition:
+# critial path is not long enough. Yet it spends ~24 cycles per byte
+# processed with 128-bit key.
 #
 # Unlike previous version hardware support detection takes place only
 # at the moment of key schedule setup, which is denoted in key->rounds.