diff --git a/src/bsdfs/mask.cpp b/src/bsdfs/mask.cpp
index 4c1bf3d8..d676e0d0 100644
--- a/src/bsdfs/mask.cpp
+++ b/src/bsdfs/mask.cpp
@@ -218,6 +218,10 @@ public:
 		return result;
 	}
 
+	Float getRoughness(const Intersection &its, int component) const {
+		return m_nestedBSDF->getRoughness(its, component);
+	}
+
 	void addChild(const std::string &name, ConfigurableObject *child) {
 		if (child->getClass()->derivesFrom(MTS_CLASS(Texture)) && name == "opacity") 
 			m_opacity = static_cast<Texture *>(child);
diff --git a/src/bsdfs/mixturebsdf.cpp b/src/bsdfs/mixturebsdf.cpp
index c0453daa..51fc444e 100644
--- a/src/bsdfs/mixturebsdf.cpp
+++ b/src/bsdfs/mixturebsdf.cpp
@@ -285,6 +285,12 @@ public:
 			BSDF::addChild(name, child);
 		}
 	}
+	
+	Float getRoughness(const Intersection &its, int component) const {
+		int bsdfIndex = m_indices[component].first;
+		component = m_indices[component].second;
+		return m_bsdfs[bsdfIndex]->getRoughness(its, component);
+	}
 
 	std::string toString() const {
 		std::ostringstream oss;
@@ -418,7 +424,6 @@ public:
 		}
 	}
 
-
 	MTS_DECLARE_CLASS()
 private:
 	std::vector<Shader *> m_bsdfShader;