diff --git a/src/mol-util/material.ts b/src/mol-util/material.ts
index a374e72a79fd1ffc1aa35b28b0881cde5d8be7a0..84adddde28204d73082b85110fbe410b3e57399f 100644
--- a/src/mol-util/material.ts
+++ b/src/mol-util/material.ts
@@ -8,9 +8,9 @@ import { NumberArray } from './type-helpers';
 import { ParamDefinition as PD } from './param-definition';
 
 export interface Material {
-    // Normalized to [0, 1] range
+    /** Normalized to [0, 1] range */
     metalness: number,
-    // Normalized to [0, 1] range
+    /** Normalized to [0, 1] range */
     roughness: number
 }