diff --git a/nx-X11/programs/Xserver/hw/nxagent/Screen.c b/nx-X11/programs/Xserver/hw/nxagent/Screen.c
index 104d431..44c6cb4 100644
--- a/nx-X11/programs/Xserver/hw/nxagent/Screen.c
+++ b/nx-X11/programs/Xserver/hw/nxagent/Screen.c
@@ -1665,7 +1665,10 @@ N/A
 
     attributes.background_pixel = nxagentBlackPixel;
 
-    nxagentGetDefaultEventMask((Mask*)&attributes.event_mask);
+    /* Assume that the mask fits in int... broken on Big Endian 64bit systems. */
+    Mask tmp_mask = attributes.event_mask;
+    nxagentGetDefaultEventMask(&tmp_mask);
+    attributes.event_mask = (int)tmp_mask;
 
     attributes.colormap = nxagentDefaultVisualColormap(nxagentDefaultVisual(pScreen));
 
diff --git a/nx-X11/programs/Xserver/hw/nxagent/Window.c b/nx-X11/programs/Xserver/hw/nxagent/Window.c
index 0a8e8c2..5ffd24d 100644
--- a/nx-X11/programs/Xserver/hw/nxagent/Window.c
+++ b/nx-X11/programs/Xserver/hw/nxagent/Window.c
@@ -335,7 +335,10 @@ FIXME: We need to set save under on the real display?
 
   if (mask & CWEventMask)
   {
-    nxagentGetEventMask(pWin, (Mask*)&attributes.event_mask);
+    /* Assume that the mask fits in int... broken on Big Endian 64bit systems. */
+    Mask tmp_mask = attributes.event_mask;
+    nxagentGetEventMask(pWin, &tmp_mask);
+    attributes.event_mask = (int)tmp_mask;
   }
   #ifdef WARNING
   else
@@ -2921,7 +2924,10 @@ FIXME: Do we need to set save unders attribute here?
 
   if (mask & CWEventMask)
   {
-    nxagentGetEventMask(pWin, (Mask*)&attributes.event_mask);
+    /* Assume that the mask fits in int... broken on Big Endian 64bit systems. */
+    Mask tmp_mask = attributes.event_mask;
+    nxagentGetEventMask(pWin, &tmp_mask);
+    attributes.event_mask = (int)tmp_mask;
   }
   #ifdef WARNING
   else
@@ -3382,7 +3388,10 @@ void nxagentSetTopLevelEventMask(pWin)
 
   if (nxagentOption(Rootless) && nxagentWindowTopLevel(pWin))
   {
-    nxagentGetEventMask(pWin, (Mask*)&attributes.event_mask);
+    /* Assume that the mask fits in int... broken on Big Endian 64bit systems. */
+    Mask tmp_mask = attributes.event_mask;
+    nxagentGetEventMask(pWin, &tmp_mask);
+    attributes.event_mask = (int)tmp_mask;
 
     XChangeWindowAttributes(nxagentDisplay, nxagentWindow(pWin), mask, &attributes);
   }