diff --git a/programs/pkey/pk_decrypt.c b/programs/pkey/pk_decrypt.c
index 6d3a1dc..1d8c959 100644
--- a/programs/pkey/pk_decrypt.c
+++ b/programs/pkey/pk_decrypt.c
@@ -97,8 +97,8 @@
                                        &entropy, (const unsigned char *) pers,
                                        strlen( pers ) ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned %d\n",
-                        ret );
+        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned -0x%04x\n",
+                        -ret );
         goto exit;
     }