diff --git a/src/system/boot/platform/atari_m68k/atari_memory_map.h b/src/system/boot/platform/atari_m68k/atari_memory_map.h
index 881450a898..2235fc276c 100644
--- a/src/system/boot/platform/atari_m68k/atari_memory_map.h
+++ b/src/system/boot/platform/atari_m68k/atari_memory_map.h
@@ -6,7 +6,9 @@
 #define ATARI_MEMORY_MAP_H
 
 /* the DMA-accessible RAM */
-#define ATARI_CHIPRAM_BASE			0x00000000
+/*#define ATARI_CHIPRAM_BASE			0x00000000*/
+/* actually, the first 2kB aren't usable */
+#define ATARI_CHIPRAM_BASE			0x00001000
 #define ATARI_CHIPRAM_MAX			0x00e00000
 #define ATARI_CHIPRAM_LAST						\
 	(ATARI_CHIPRAM_BASE + (ATARI_CHIPRAM_MAX - 1))
diff --git a/src/system/boot/platform/atari_m68k/mmu.cpp b/src/system/boot/platform/atari_m68k/mmu.cpp
index e3dfbd872a..b4631f1940 100644
--- a/src/system/boot/platform/atari_m68k/mmu.cpp
+++ b/src/system/boot/platform/atari_m68k/mmu.cpp
@@ -625,7 +625,7 @@ mmu_init(void)
 
 	// st ram as 1st range
 	gKernelArgs.physical_memory_range[0].start = ATARI_CHIPRAM_BASE;
-	gKernelArgs.physical_memory_range[0].size = *TOSVARphystop;
+	gKernelArgs.physical_memory_range[0].size = *TOSVARphystop - ATARI_CHIPRAM_BASE;
 	gKernelArgs.num_physical_memory_ranges = 1;
 
 	// fast ram as 2nd range