diff --git a/glm/gtc/quaternion.hpp b/glm/gtc/quaternion.hpp
index a859eede..f6238ccd 100644
--- a/glm/gtc/quaternion.hpp
+++ b/glm/gtc/quaternion.hpp
@@ -122,13 +122,13 @@ namespace quaternion ///< GLM_GTC_quaternion extension: Quaternion types and fun
 	/// \addtogroup gtc_quaternion
 	///@{
 
-	//! Returns the length of the quaternion x. 
+	//! Returns the length of the quaternion. 
 	//! From GLM_GTC_quaternion extension.
     template <typename T> 
 	typename detail::tquat<T>::value_type length(
 		detail::tquat<T> const & q);
 
-    //! Returns the normalized quaternion of from x. 
+    //! Returns the normalized quaternion. 
 	//! From GLM_GTC_quaternion extension.
 	template <typename T> 
 	detail::tquat<T> normalize(
diff --git a/glm/gtc/quaternion.inl b/glm/gtc/quaternion.inl
index 742fbde3..27a5c541 100644
--- a/glm/gtc/quaternion.inl
+++ b/glm/gtc/quaternion.inl
@@ -416,7 +416,7 @@ namespace quaternion{
 	)
     {
 		T angle = acos(dot(x, y));
-		return (sin((1 - a) * angle) * x + sin(a * angle) * y) / sin(angle);
+		return (sin((T(1) - a) * angle) * x + sin(a * angle) * y) / sin(angle);
 	}
 
     template <typename T> 
diff --git a/test/gtc/gtc_quaternion.cpp b/test/gtc/gtc_quaternion.cpp
index 72bf13a4..689cfe27 100644
--- a/test/gtc/gtc_quaternion.cpp
+++ b/test/gtc/gtc_quaternion.cpp
@@ -2,17 +2,82 @@
 // OpenGL Mathematics Copyright (c) 2005 - 2011 G-Truc Creation (www.g-truc.net)
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 // Created : 2010-09-16
-// Updated : 2010-05-07
+// Updated : 2011-05-25
 // Licence : This source is under MIT licence
 // File    : test/gtc/quaternion.cpp
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 #include <glm/glm.hpp>
 #include <glm/gtc/quaternion.hpp>
+#include <glm/gtx/epsilon.hpp>
+
+int test_quat_type()
+{
+    glm::quat A;
+    glm::dquat B;
+    
+    return 0;
+}
+
+int test_quat_slerp()
+{
+    int Error = 0;
+    
+    glm::quat A(0.0f, glm::vec3(0, 0, 1));
+    glm::quat B(90.0f, glm::vec3(0, 0, 1));
+    glm::quat C = glm::mix(A, B, 0.5f);
+    
+    Error += C != glm::quat(45.f, glm::vec3(0, 0, 1)) ? 0 : 1;
+
+    return Error;
+}
+
+int test_quat_length()
+{
+    int Error = 0;
+
+    float A = glm::length(glm::quat(45.0f, glm::vec3(0, 0, 1)));
+    Error += A == 1.0f ? 0 : 1;
+    float B = glm::length(glm::quat(90.0f, glm::vec3(0, 0, 2)));
+    Error += B == 2.0f ? 0 : 1;
+
+    return Error;
+}
+
+int test_quat_normalize()
+{
+    int Error = 0;
+ 
+    {
+        glm::quat Q(45.0f, glm::vec3(0, 0, 1));
+        glm::quat N = glm::normalize(Q);
+        float L = glm::length(N);
+        Error += L == 1.0f ? 0 : 1;
+    }
+    {
+        glm::quat Q(45.0f, glm::vec3(0, 0, 2));
+        glm::quat N = glm::normalize(Q);
+        float L = glm::length(N);
+        Error += L == 1.0f ? 0 : 1;
+    }
+    {
+        glm::quat Q(45.0f, glm::vec3(1, 2, 3));
+        glm::quat N = glm::normalize(Q);
+        float L = glm::length(N);
+        Error += L == 1.0f ? 0 : 1;
+    }
+
+    return Error;
+}
 
 int main()
 {
 	int Error = 0;
+    
+    Error += test_quat_type();
+    Error += test_quat_slerp();
+    Error += test_quat_length();
+    Error += test_quat_normalize();
 
 	return Error;
 }
diff --git a/test/gtx/CMakeLists.txt b/test/gtx/CMakeLists.txt
index fca74f16..48258987 100644
--- a/test/gtx/CMakeLists.txt
+++ b/test/gtx/CMakeLists.txt
@@ -1,5 +1,6 @@
 glmCreateTestGTC(gtx_bit)
 glmCreateTestGTC(gtx_noise)
+glmCreateTestGTC(gtx_quaternion)
 glmCreateTestGTC(gtx_rotate_vector)
 glmCreateTestGTC(gtx_simd_vec4)
 glmCreateTestGTC(gtx_simd_mat4)
diff --git a/test/gtx/gtx_quaternion.cpp b/test/gtx/gtx_quaternion.cpp
new file mode 100644
index 00000000..241f572c
--- /dev/null
+++ b/test/gtx/gtx_quaternion.cpp
@@ -0,0 +1,53 @@
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// OpenGL Mathematics Copyright (c) 2005 - 2011 G-Truc Creation (www.g-truc.net)
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// Created : 2011-05-25
+// Updated : 2011-05-25
+// Licence : This source is under MIT licence
+// File    : test/gtx/quaternion.cpp
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+#include <glm/glm.hpp>
+#include <glm/gtx/quaternion.hpp>
+#include <glm/gtx/epsilon.hpp>
+
+int test_quat_angle()
+{
+    int Error = 0;
+    
+    {
+        glm::quat Q(45.0f, glm::vec3(0, 0, 1));
+        glm::quat N = glm::normalize(Q);
+        float L = glm::length(N);
+        Error += L == 1.0f ? 0 : 1;
+        float A = glm::angle(N);
+        Error += glm::equalEpsilon(A, 45.0f, 0.01f) ? 0 : 1;
+    }
+    {
+        glm::quat Q(45.0f, glm::vec3(0, 0, 2));
+        glm::quat N = glm::normalize(Q);
+        float L = glm::length(N);
+        Error += L == 1.0f ? 0 : 1;
+        float A = glm::angle(N);
+        Error += glm::equalEpsilon(A, 45.0f, 0.01f) ? 0 : 1;
+    }
+    {
+        glm::quat Q(45.0f, glm::vec3(1, 2, 3));
+        glm::quat N = glm::normalize(Q);
+        float L = glm::length(N);
+        Error += L == 1.0f ? 0 : 1;
+        float A = glm::angle(N);
+        Error += glm::equalEpsilon(A, 45.0f, 0.01f) ? 0 : 1;
+    }
+    
+    return Error;
+}
+
+int main()
+{
+	int Error = 0;
+    
+    Error += test_quat_angle();
+
+	return Error;
+}