diff --git a/hw/xwin/InitOutput.c b/hw/xwin/InitOutput.c
index 88bc85a44..ae02c1797 100644
--- a/hw/xwin/InitOutput.c
+++ b/hw/xwin/InitOutput.c
@@ -1010,7 +1010,7 @@ winCheckDisplayNumber(void)
     int nDisp;
     HANDLE mutex;
     char name[MAX_PATH];
-    char *pszPrefix = '\0';
+    const char *pszPrefix = '\0';
     OSVERSIONINFO osvi = { 0 };
 
     /* Check display range */