diff --git a/programs/pkey/key_app_writer.c b/programs/pkey/key_app_writer.c
index 13602c2e5..ebf6ad134 100644
--- a/programs/pkey/key_app_writer.c
+++ b/programs/pkey/key_app_writer.c
@@ -173,7 +173,7 @@ static int write_private_key( mbedtls_pk_context *key, const char *output_file )
             return( ret );
 
         len = ret;
-        c = output_buf + sizeof(output_buf) - len - 1;
+        c = output_buf + sizeof(output_buf) - len;
     }
 
     if( ( f = fopen( output_file, "w" ) ) == NULL )