diff --git a/src/trident_driver.c b/src/trident_driver.c
index b3710b7..0b489a3 100644
--- a/src/trident_driver.c
+++ b/src/trident_driver.c
@@ -1854,7 +1854,7 @@ TRIDENTPreInit(ScrnInfoPtr pScrn, int flags)
     vgaHWPtr hwp;
     MessageType from;
     CARD8 videoram, videorammask;
-    char *ramtype = NULL, *chipset = NULL;
+    const char *ramtype = NULL, *chipset = NULL;
     Bool Support24bpp;
     int vgaIOBase;
     float mclk;