diff --git a/src/radeon_driver.c b/src/radeon_driver.c
index d039920..d5704d3 100644
--- a/src/radeon_driver.c
+++ b/src/radeon_driver.c
@@ -1403,6 +1403,15 @@ static void RADEONInitMemoryMap(ScrnInfoPtr pScrn)
     if (aper_size > mem_size)
 	mem_size = aper_size;
 
+    /* don't map the whole FB in the internal address space.
+     * we don't currently use fb space larger than the aperture
+     * size and on cards with 1 GB of vram, this can overflow
+     * the internal top of gart calculation on some systems.
+     * See fdo bug 24301.
+     */
+    if (mem_size > aper_size)
+	mem_size = aper_size;
+
 #ifdef XF86DRI
     /* Apply memory map limitation if using an old DRI */
     if (info->directRenderingEnabled && !info->dri->newMemoryMap) {