diff --git a/programs/pkey/rsa_sign.c b/programs/pkey/rsa_sign.c
index 3ff411a..54f60c5 100644
--- a/programs/pkey/rsa_sign.c
+++ b/programs/pkey/rsa_sign.c
@@ -59,7 +59,7 @@
     int ret;
     size_t i;
     mbedtls_rsa_context rsa;
-    unsigned char hash[20];
+    unsigned char hash[32];
     unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
     char filename[512];