diff --git a/glm/gtx/intersect.inl b/glm/gtx/intersect.inl
index 0bb7d7f8..904d6cca 100644
--- a/glm/gtx/intersect.inl
+++ b/glm/gtx/intersect.inl
@@ -14,7 +14,7 @@ namespace glm
 		typename genType::value_type d = glm::dot(dir, planeNormal);
 		typename genType::value_type Epsilon = std::numeric_limits<typename genType::value_type>::epsilon();
 
-		if(d < Epsilon)
+		if(d < -Epsilon)
 		{
 			intersectionDistance = glm::dot(planeOrig - orig, planeNormal) / d;
 			return true;
diff --git a/readme.md b/readme.md
index efe5bb8b..6c7a6255 100644
--- a/readme.md
+++ b/readme.md
@@ -87,6 +87,7 @@ glm::mat4 camera(float Translate, glm::vec2 const & Rotate)
 #### Fixes:
 - Fixed GTC_packing test failing on GCC x86 due to denorms #212 #577
 - Fixed POPCNT optimization build in Clang #512
+- Fixed intersectRayPlane returns true in parallel case #578
 
 ---
 ### [GLM 0.9.8.3](https://github.com/g-truc/glm/releases/tag/0.9.8.3) - 2016-11-12