diff --git a/riscv/decode.h b/riscv/decode.h
index 51ecbebc..a4bbac66 100644
--- a/riscv/decode.h
+++ b/riscv/decode.h
@@ -245,7 +245,4 @@ private:
 #define set_field(reg, mask, val) \
   (((reg) & ~(std::remove_cv<decltype(reg)>::type)(mask)) | (((std::remove_cv<decltype(reg)>::type)(val) * ((mask) & ~((mask) << 1))) & (std::remove_cv<decltype(reg)>::type)(mask)))
 
-#define DEBUG_START             0x0
-#define DEBUG_END               (0x1000 - 1)
-
 #endif
diff --git a/riscv/mmu.cc b/riscv/mmu.cc
index b080697e..e95b5755 100644
--- a/riscv/mmu.cc
+++ b/riscv/mmu.cc
@@ -6,6 +6,7 @@
 #include "simif.h"
 #include "processor.h"
 #include "decode_macros.h"
+#include "platform.h"
 
 mmu_t::mmu_t(simif_t* sim, endianness_t endianness, processor_t* proc, reg_t cache_blocksz)
  : sim(sim), proc(proc), blocksz(cache_blocksz),
@@ -140,8 +141,8 @@ reg_t reg_from_bytes(size_t len, const uint8_t* bytes)
 bool mmu_t::mmio_ok(reg_t paddr, access_type UNUSED type)
 {
   // Disallow access to debug region when not in debug mode
-  static_assert(DEBUG_START == 0);
-  if (/* paddr >= DEBUG_START && */ paddr <= DEBUG_END && proc && !proc->state.debug_mode)
+  reg_t debug_start = DEBUG_START; // suppress -Wtype-limits
+  if (paddr >= debug_start && paddr - debug_start < DEBUG_SIZE && proc && !proc->state.debug_mode)
     return false;
 
   return true;
diff --git a/riscv/platform.h b/riscv/platform.h
index c8a5bf4b..5b794da2 100644
--- a/riscv/platform.h
+++ b/riscv/platform.h
@@ -19,5 +19,7 @@
 #define NS16550_INTERRUPT_ID 1
 #define EXT_IO_BASE        0x40000000
 #define DRAM_BASE          0x80000000
+#define DEBUG_START        0x0
+#define DEBUG_SIZE         0x1000
 
 #endif