diff --git a/programs/pkey/dh_client.c b/programs/pkey/dh_client.c
index 10b9b7a..2909d1d 100644
--- a/programs/pkey/dh_client.c
+++ b/programs/pkey/dh_client.c
@@ -75,7 +75,7 @@
 
     unsigned char *p, *end;
     unsigned char buf[2048];
-    unsigned char hash[20];
+    unsigned char hash[32];
     const char *pers = "dh_client";
 
     mbedtls_entropy_context entropy;