diff --git a/retroshare-gui/src/gui/feeds/GxsChannelPostItem.cpp b/retroshare-gui/src/gui/feeds/GxsChannelPostItem.cpp
index 4db137ff3..4b83f76b4 100644
--- a/retroshare-gui/src/gui/feeds/GxsChannelPostItem.cpp
+++ b/retroshare-gui/src/gui/feeds/GxsChannelPostItem.cpp
@@ -38,6 +38,7 @@
 #include "gui/gxschannels/CreateGxsChannelMsg.h"
 
 #include <iostream>
+#include <cmath>
 
 /****
  * #define DEBUG_ITEM 1