diff --git a/media/libeffects/visualizer/EffectVisualizer.cpp b/media/libeffects/visualizer/EffectVisualizer.cpp
index 0e82339..c33f9f5 100644
--- a/media/libeffects/visualizer/EffectVisualizer.cpp
+++ b/media/libeffects/visualizer/EffectVisualizer.cpp
@@ -594,7 +594,7 @@
                     deltaSmpl = CAPTURE_BUF_SIZE;
                 }
 
-                int32_t capturePoint = pContext->mCaptureIdx - deltaSmpl;
+                int32_t capturePoint = (int32_t)pContext->mCaptureIdx - deltaSmpl;
                 // a negative capturePoint means we wrap the buffer.
                 if (capturePoint < 0) {
                     uint32_t size = -capturePoint;