diff --git a/sjsonnet/src/sjsonnet/stdlib/MathModule.scala b/sjsonnet/src/sjsonnet/stdlib/MathModule.scala
index 65612cf8..8ec43255 100644
--- a/sjsonnet/src/sjsonnet/stdlib/MathModule.scala
+++ b/sjsonnet/src/sjsonnet/stdlib/MathModule.scala
@@ -552,7 +552,7 @@ object MathModule extends AbstractFunctionModule {
      * The official docs list std.mantissa(x) as a mathematical function.
      */
     builtin("mantissa", "x") { (pos, ev, x: Double) =>
-      if (x == 0) 0.0
+      if (x == 0) x
       else {
         val bits = java.lang.Double.doubleToRawLongBits(x)
         val absBits = bits & 0x7fffffffffffffffL
diff --git a/sjsonnet/test/resources/new_test_suite/mantissa_negative_zero.jsonnet b/sjsonnet/test/resources/new_test_suite/mantissa_negative_zero.jsonnet
new file mode 100644
index 00000000..442d2241
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/mantissa_negative_zero.jsonnet
@@ -0,0 +1,7 @@
+// std.mantissa must preserve the sign of negative zero.
+// assertEqual cannot distinguish -0.0 from 0.0 (IEEE equality),
+// so we observe the sign through std.toString rendering.
+std.toString(std.mantissa(0 * -1)) == "-0" &&
+std.toString(std.mantissa(0)) == "0" &&
+std.toString(std.mantissa(1.5)) == "0.75" &&
+std.toString(std.mantissa(-1.5)) == "-0.75"
diff --git a/sjsonnet/test/resources/new_test_suite/mantissa_negative_zero.jsonnet.golden b/sjsonnet/test/resources/new_test_suite/mantissa_negative_zero.jsonnet.golden
new file mode 100644
index 00000000..27ba77dd
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/mantissa_negative_zero.jsonnet.golden
@@ -0,0 +1 @@
+true