diff --git a/src/LinearMath/btHashMap.h b/src/LinearMath/btHashMap.h
index 0a61482ea..1fb84d640 100644
--- a/src/LinearMath/btHashMap.h
+++ b/src/LinearMath/btHashMap.h
@@ -47,7 +47,7 @@ struct btHashString
 			return( ret );
 	}
 
-	const bool equals(const btHashString& other) const
+	bool equals(const btHashString& other) const
 	{
 		return (m_string == other.m_string) ||
 			(0==portableStringCompare(m_string,other.m_string));
diff --git a/src/LinearMath/btQuaternion.h b/src/LinearMath/btQuaternion.h
index f530c71df..15cf5f868 100644
--- a/src/LinearMath/btQuaternion.h
+++ b/src/LinearMath/btQuaternion.h
@@ -285,10 +285,17 @@ public:
 			btScalar d = btScalar(1.0) / btSin(theta);
 			btScalar s0 = btSin((btScalar(1.0) - t) * theta);
 			btScalar s1 = btSin(t * theta);   
-			return btQuaternion((m_floats[0] * s0 + q.x() * s1) * d,
-				(m_floats[1] * s0 + q.y() * s1) * d,
-				(m_floats[2] * s0 + q.z() * s1) * d,
-				(m_floats[3] * s0 + q.m_floats[3] * s1) * d);
+                        if (dot(q) < 0) // Take care of long angle case see http://en.wikipedia.org/wiki/Slerp
+                          return btQuaternion((m_floats[0] * s0 + -q.x() * s1) * d,
+                                              (m_floats[1] * s0 + -q.y() * s1) * d,
+                                              (m_floats[2] * s0 + -q.z() * s1) * d,
+                                              (m_floats[3] * s0 + -q.m_floats[3] * s1) * d);
+                        else
+                          return btQuaternion((m_floats[0] * s0 + q.x() * s1) * d,
+                                              (m_floats[1] * s0 + q.y() * s1) * d,
+                                              (m_floats[2] * s0 + q.z() * s1) * d,
+                                              (m_floats[3] * s0 + q.m_floats[3] * s1) * d);
+                        
 		}
 		else
 		{