diff --git a/include/mitsuba/core/autodiff.h b/include/mitsuba/core/autodiff.h
index 7cb6eec5..990bbebd 100644
--- a/include/mitsuba/core/autodiff.h
+++ b/include/mitsuba/core/autodiff.h
@@ -254,6 +254,12 @@ public:
 		grad *= v;
 		return *this;
 	}
+	
+	inline DScalar1& operator*=(const DScalar1 &v) {
+		grad = v.grad * value + grad * v.value;
+		value *= v.value;
+		return *this;
+	}
 
 	/// @}
 	// ======================================================================