diff --git a/shaders/pbr.glsl b/shaders/pbr.glsl
index 9196edc..0add433 100644
--- a/shaders/pbr.glsl
+++ b/shaders/pbr.glsl
@@ -23,7 +23,7 @@ float PBR_GetSpecularOld( in float cosine , in float alpha )
 {
 	float cs = cosine * cosine;
 	float as = alpha * alpha;
-	return 1. / ( cosine + sqrt( cs + as - cs * as ) );
+	return clamp( 1. / ( cosine + sqrt( cs + as - cs * as ) ) , 0 , 1 );
 }
 
 // Precompute some of the material's properties. This is independant of the