diff --git a/hw/xfree86/os-support/linux/lnx_agp.c b/hw/xfree86/os-support/linux/lnx_agp.c
index c65f1e3f3..a5f041162 100644
--- a/hw/xfree86/os-support/linux/lnx_agp.c
+++ b/hw/xfree86/os-support/linux/lnx_agp.c
@@ -264,7 +264,7 @@ xf86DeallocateGARTMemory(int screenNum, int key)
 	}
 
 #ifdef __linux__
-	if (ioctl(gartFd, AGPIOC_DEALLOCATE, (int *)key) != 0) {
+	if (ioctl(gartFd, AGPIOC_DEALLOCATE, (int *)(uintptr_t)key) != 0) {
 #else
 	if (ioctl(gartFd, AGPIOC_DEALLOCATE, &key) != 0) {
 #endif