diff --git a/CHANGELOG.md b/CHANGELOG.md
index a1a5a4b..0c98e4b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,11 @@
 ## 0.12.5
 
 - Add `isA()` to create `TypeMatcher` instances in a more fluent way.
+- **Potentially breaking bug fix**. Ordering matchers no longer treat objects
+  with a partial ordering (such as NaN for double values) as if they had a
+  complete ordering. For instance `greaterThan` now compares with the `>`
+  operator rather not `<` and not `=`. This could cause tests which relied on
+  this bug to start failing.
 
 ## 0.12.4
 
diff --git a/lib/src/numeric_matchers.dart b/lib/src/numeric_matchers.dart
index c84a2f3..62ca3fd 100644
--- a/lib/src/numeric_matchers.dart
+++ b/lib/src/numeric_matchers.dart
@@ -77,7 +77,8 @@
     if (value == _high) {
       return _highMatchValue;
     }
-    return true;
+    // Value may still be outside if range if it can't be compared.
+    return value > _low && value < _high;
   }
 
   @override
diff --git a/lib/src/order_matchers.dart b/lib/src/order_matchers.dart
index b94231f..c492595 100644
--- a/lib/src/order_matchers.dart
+++ b/lib/src/order_matchers.dart
@@ -80,8 +80,10 @@
       return _equalValue;
     } else if (item < _value) {
       return _lessThanValue;
-    } else {
+    } else if (item > _value) {
       return _greaterThanValue;
+    } else {
+      return false;
     }
   }
 
diff --git a/pubspec.yaml b/pubspec.yaml
index ecd7d3c..f109db1 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: matcher
-version: 0.12.5-dev
+version: 0.12.5
 
 description: >-
   Support for specifying test expectations via an extensible Matcher class.
diff --git a/test/numeric_matchers_test.dart b/test/numeric_matchers_test.dart
index a85f13b..c85a0e6 100644
--- a/test/numeric_matchers_test.dart
+++ b/test/numeric_matchers_test.dart
@@ -85,4 +85,15 @@
     shouldFail('not a num', inClosedOpenRange(0, 1),
         endsWith('not an <Instance of \'num\'>'));
   });
+
+  group('NaN', () {
+    test('inInclusiveRange', () {
+      shouldFail(
+          double.nan,
+          inExclusiveRange(double.negativeInfinity, double.infinity),
+          "Expected: be in range from "
+          "-Infinity (exclusive) to Infinity (exclusive) "
+          "Actual: <NaN>");
+    });
+  });
 }
diff --git a/test/order_matchers_test.dart b/test/order_matchers_test.dart
index ff09b6c..221b06c 100644
--- a/test/order_matchers_test.dart
+++ b/test/order_matchers_test.dart
@@ -115,4 +115,36 @@
         "Actual: <-1> "
         "Which: is not a non-negative value");
   });
+
+  group('NaN', () {
+    test('greaterThan', () {
+      shouldFail(
+          double.nan,
+          greaterThan(10),
+          "Expected: a value greater than <10> "
+          "Actual: <NaN> "
+          "Which: is not a value greater than <10>");
+      shouldFail(
+          10,
+          greaterThan(double.nan),
+          "Expected: a value greater than <NaN> "
+          "Actual: <10> "
+          "Which: is not a value greater than <NaN>");
+    });
+
+    test('lessThanOrEqualTo', () {
+      shouldFail(
+          double.nan,
+          lessThanOrEqualTo(10),
+          "Expected: a value less than or equal to <10> "
+          "Actual: <NaN> "
+          "Which: is not a value less than or equal to <10>");
+      shouldFail(
+          10,
+          lessThanOrEqualTo(double.nan),
+          "Expected: a value less than or equal to <NaN> "
+          "Actual: <10> "
+          "Which: is not a value less than or equal to <NaN>");
+    });
+  });
 }