diff --git a/glm/ext/quaternion_common.hpp b/glm/ext/quaternion_common.hpp
index f519d559..c9163609 100644
--- a/glm/ext/quaternion_common.hpp
+++ b/glm/ext/quaternion_common.hpp
@@ -96,7 +96,7 @@ namespace glm
 	/// @tparam T A floating-point scalar type
 	/// @tparam Q A value from qualifier enum
 	template<typename T, qualifier Q>
-	GLM_FUNC_DECL qua<T, Q> conjugate(qua<T, Q> const& q);
+	GLM_FUNC_DECL GLM_CONSTEXPR qua<T, Q> conjugate(qua<T, Q> const& q);
 
 	/// Returns the q inverse.
 	///
diff --git a/glm/ext/quaternion_common.inl b/glm/ext/quaternion_common.inl
index 0e4a3bb2..4d6869e5 100644
--- a/glm/ext/quaternion_common.inl
+++ b/glm/ext/quaternion_common.inl
@@ -110,7 +110,7 @@ namespace glm
     }
 
 	template<typename T, qualifier Q>
-	GLM_FUNC_QUALIFIER qua<T, Q> conjugate(qua<T, Q> const& q)
+	GLM_FUNC_QUALIFIER GLM_CONSTEXPR qua<T, Q> conjugate(qua<T, Q> const& q)
 	{
 		return qua<T, Q>(q.w, -q.x, -q.y, -q.z);
 	}