diff --git a/src/main.rs b/src/main.rs
index 3e99a2a..4c333eb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -301,7 +301,7 @@ fn main() {
                 // == // Issue the necessary gl:: commands to draw your scene here
                 simple_shader.activate();
                 // build and send the transform matrix (start from identity)
-                let mut transform = glm::identity();
+                let mut transform: glm::Mat4 = glm::identity();
                 // modify element (0,0) here; change indices to test a, b, c, d, e, f, etc.
                 transform[(0,0)] = elapsed.sin(); 
                 gl::UniformMatrix4fv(transform_loc, 1, gl::FALSE, transform.as_ptr());