diff --git a/src/quick/scenegraph/qsgcontext.cpp b/src/quick/scenegraph/qsgcontext.cpp
index b5bdbde3ad85cf766daaacea114cc03cbca36c39..90102f1110976b2a5256946e354daf98430ad6c8 100644
--- a/src/quick/scenegraph/qsgcontext.cpp
+++ b/src/quick/scenegraph/qsgcontext.cpp
@@ -161,6 +161,7 @@ public:
         , m_time(0)
         , m_vsync(0)
         , m_mode(VSyncMode)
+        , m_lag(0)
         , m_bad(0)
         , m_good(0)
     {