diff --git a/src/modules/Gmp/testsuite.in b/src/modules/Gmp/testsuite.in
index 6c8c34e3d3d42847b4d96e872e90e068f3257233..267273f3353eb17de7c65eb582bb3ca00a895cbd 100644
--- a/src/modules/Gmp/testsuite.in
+++ b/src/modules/Gmp/testsuite.in
@@ -67,6 +67,7 @@ cond( [[ master()->resolv("Gmp")->mpz ]],
 
   test_true(catch(Gmp.mpz("abcd", 47)))
   test_true(catch(Gmp.mpz(-17)->digits(256)))
+  test_eq(Gmp.mpz(17)->digits(256), "\021");
   test_eq(Gmp.mpz(4711)->size(2), 13)
   test_true(catch(Gmp.mpz(17) + 18 + "19"))
   test_true(catch(Gmp.mpz(17) - 18 - "19"))