diff --git a/winsrc/gui.cpp b/winsrc/gui.cpp
index 161f99d62..8929a05ce 100644
--- a/winsrc/gui.cpp
+++ b/winsrc/gui.cpp
@@ -33,6 +33,7 @@ void dbp(char *str, ...)
 
 int GraphBuffer[MAX_GRAPH_TRACE_LEN];
 int GraphTraceLen;
+int PlotGridX, PlotGridY;
 
 HPEN GreyPenLite, GreyPen, GreenPen, WhitePen, YellowPen;
 HBRUSH GreenBrush, YellowBrush;