diff --git a/opengl/tests/hwc/hwcCommit.cpp b/opengl/tests/hwc/hwcCommit.cpp
index 1bcb860..5d7f810 100644
--- a/opengl/tests/hwc/hwcCommit.cpp
+++ b/opengl/tests/hwc/hwcCommit.cpp
@@ -162,7 +162,7 @@
 // Local types
 class Rectangle {
 public:
-    Rectangle(uint32_t graphicFormat = defaultFormat,
+    explicit Rectangle(uint32_t graphicFormat = defaultFormat,
               HwcTestDim dfDim = HwcTestDim(1, 1),
               HwcTestDim sDim = HwcTestDim(1, 1));
     void setSourceDim(HwcTestDim dim);