diff --git a/Source/OpenTK/Math/Quaternion.cs b/Source/OpenTK/Math/Quaternion.cs
index da62d7c4..8ee0fc01 100644
--- a/Source/OpenTK/Math/Quaternion.cs
+++ b/Source/OpenTK/Math/Quaternion.cs
@@ -135,7 +135,7 @@ namespace OpenTK
         public Vector4 ToAxisAngle()
         {
             Quaternion q = this;
-            if (q.W > 1.0f)
+            if (Math.Abs(q.W) > 1.0f)
                 q.Normalize();
 
             Vector4 result = new Vector4();
diff --git a/Source/OpenTK/Math/Quaterniond.cs b/Source/OpenTK/Math/Quaterniond.cs
index 9f116f93..46aec949 100644
--- a/Source/OpenTK/Math/Quaterniond.cs
+++ b/Source/OpenTK/Math/Quaterniond.cs
@@ -135,7 +135,7 @@ namespace OpenTK
         public Vector4d ToAxisAngle()
         {
             Quaterniond q = this;
-            if (q.W > 1.0f)
+            if (Math.Abs(q.W) > 1.0f)
                 q.Normalize();
 
             Vector4d result = new Vector4d();