diff --git a/media/libmedia/Visualizer.cpp b/media/libmedia/Visualizer.cpp
index 47e96e5..32cdb49 100644
--- a/media/libmedia/Visualizer.cpp
+++ b/media/libmedia/Visualizer.cpp
@@ -184,7 +184,7 @@
 
     status_t status = NO_ERROR;
     if (mEnabled) {
-        int32_t replySize = mCaptureSize;
+        uint32_t replySize = mCaptureSize;
         status_t status = command(VISU_CMD_CAPTURE, 0, NULL, &replySize, waveform);
         if (replySize == 0) {
             status = NOT_ENOUGH_DATA;