diff --git a/shaders/pbr-qt.frag b/shaders/pbr-qt.frag
index 773b1291..401f7b56 100644
--- a/shaders/pbr-qt.frag
+++ b/shaders/pbr-qt.frag
@@ -361,6 +361,7 @@ void main()
     }
     
     roughness = min(0.99, roughness);
+    metalness = min(0.99, metalness);
 
     gl_FragColor = metalRoughFunction(vec4(color, alpha),
                                       metalness,