diff --git a/include/mgba/internal/arm/arm.h b/include/mgba/internal/arm/arm.h
index 55e847c7f..a1f040c8b 100644
--- a/include/mgba/internal/arm/arm.h
+++ b/include/mgba/internal/arm/arm.h
@@ -124,7 +124,7 @@ struct ARMMemory {
 	uint32_t (*storeMultiple)(struct ARMCore*, uint32_t baseAddress, int mask, enum LSMDirection direction,
 	                          int* cycleCounter);
 
-	uint32_t* activeRegion;
+	const uint32_t* activeRegion;
 	uint32_t activeMask;
 	uint32_t activeSeqCycles32;
 	uint32_t activeSeqCycles16;
diff --git a/include/mgba/internal/lr35902/lr35902.h b/include/mgba/internal/lr35902/lr35902.h
index c5bfd1381..4f2a29c71 100644
--- a/include/mgba/internal/lr35902/lr35902.h
+++ b/include/mgba/internal/lr35902/lr35902.h
@@ -56,7 +56,7 @@ struct LR35902Memory {
 
 	int (*currentSegment)(struct LR35902Core*, uint16_t address);
 
-	uint8_t* activeRegion;
+	const uint8_t* activeRegion;
 	uint16_t activeMask;
 	uint16_t activeRegionEnd;
 	void (*setActiveRegion)(struct LR35902Core*, uint16_t address);