diff --git a/test/format-type-x-test.js b/test/format-type-x-test.js
index 1b6c5d0..49bd8ed 100644
--- a/test/format-type-x-test.js
+++ b/test/format-type-x-test.js
@@ -50,6 +50,12 @@ tape("format(\"x\") rounds non-integers", function(test) {
   test.end();
 });
 
+tape("format(\"x\") can format negative zero as zero", function(test) {
+  test.equal(format.format("x")(-0), "0");
+  test.equal(format.format("x")(-1e-12), "0");
+  test.end();
+});
+
 tape("format(\"x\") does not consider -0xeee to be positive", function(test) {
   test.equal(format.format("x")(-0xeee), "-eee");
   test.end();
@@ -65,6 +71,12 @@ tape("format(\"#X\") returns the expected hexadecimal (uppercase) string with pr
   test.end();
 });
 
+tape("format(\"X\") can format negative zero as zero", function(test) {
+  test.equal(format.format("X")(-0), "0");
+  test.equal(format.format("X")(-1e-12), "0");
+  test.end();
+});
+
 tape("format(\"X\") does not consider -0xeee to be positive", function(test) {
   test.equal(format.format("X")(-0xeee), "-EEE");
   test.end();