diff --git a/src/system/boot/platform/atari_m68k/mmu.cpp b/src/system/boot/platform/atari_m68k/mmu.cpp
index d046241c12..6ed808259c 100644
--- a/src/system/boot/platform/atari_m68k/mmu.cpp
+++ b/src/system/boot/platform/atari_m68k/mmu.cpp
@@ -591,8 +591,8 @@ mmu_init(void)
 	gKernelArgs.num_physical_allocated_ranges = 1;
 		// remember the start of the allocated physical pages
 
-	// enable transparent translation of the first 32 MB
-	gMMUOps->set_tt(0, ATARI_CHIPRAM_BASE, 0x02000000, 0);
+	// enable transparent translation of the first 256 MB
+	gMMUOps->set_tt(0, ATARI_CHIPRAM_BASE, 0x10000000, 0);
 	// enable transparent translation of the 16MB ST shadow range for I/O
 	gMMUOps->set_tt(1, ATARI_SHADOW_BASE, 0x01000000, 0);