Address user reported coverity issues.
diff --git a/programs/pkey/pk_sign.c b/programs/pkey/pk_sign.c
index 322e8af..daf08a9 100644
--- a/programs/pkey/pk_sign.c
+++ b/programs/pkey/pk_sign.c
@@ -142,6 +142,7 @@
     if( fwrite( buf, 1, olen, f ) != olen )
     {
         mbedtls_printf( "failed\n  ! fwrite failed\n\n" );
+        fclose( f );
         goto exit;
     }