diff --git a/user/src/com/google/gwt/safecss/shared/SafeStylesUtils.java b/user/src/com/google/gwt/safecss/shared/SafeStylesUtils.java
index 84f76a2..a225603 100644
--- a/user/src/com/google/gwt/safecss/shared/SafeStylesUtils.java
+++ b/user/src/com/google/gwt/safecss/shared/SafeStylesUtils.java
@@ -488,7 +488,7 @@
    * Set the z-index css property.
    */
   public static SafeStyles forZIndex(int value) {
-    return new SafeStylesString("zIndex: " + value + ";");
+    return new SafeStylesString("z-index: " + value + ";");
   }
 
   /**
diff --git a/user/test/com/google/gwt/safecss/shared/GwtSafeStylesUtilsTest.java b/user/test/com/google/gwt/safecss/shared/GwtSafeStylesUtilsTest.java
index 2c6a37b..29b97fd 100644
--- a/user/test/com/google/gwt/safecss/shared/GwtSafeStylesUtilsTest.java
+++ b/user/test/com/google/gwt/safecss/shared/GwtSafeStylesUtilsTest.java
@@ -92,7 +92,7 @@
   }
 
   public void testForZIndex() {
-    assertEquals("zIndex: 5;", SafeStylesUtils.forZIndex(5).asString());
+    assertEquals("z-index: 5;", SafeStylesUtils.forZIndex(5).asString());
   }
 
   public void testFromTrustedNameAndValue() {