diff --git a/include/mgba/internal/ds/io.h b/include/mgba/internal/ds/io.h
index 3bba5792a..e1ca2bc4a 100644
--- a/include/mgba/internal/ds/io.h
+++ b/include/mgba/internal/ds/io.h
@@ -97,6 +97,8 @@ enum DSIORegisters {
 	DS_REG_IE_HI = 0x212,
 	DS_REG_IF_LO = 0x214,
 	DS_REG_IF_HI = 0x216,
+
+	DS_REG_POSTFLG = 0x300,
 };
 
 enum DS7IORegisters {
@@ -114,7 +116,6 @@ enum DS7IORegisters {
 	// Memory control
 	DS7_REG_VRAMSTAT = 0x240,
 	DS7_REG_WRAMSTAT = 0x241,
-	DS7_REG_POSTFLG = 0x300,
 	DS7_REG_HALTCNT = 0x301,
 	DS7_REG_POWCNT2 = 0x304,
 	DS7_REG_BIOSPROT_LO = 0x308,
@@ -257,7 +258,6 @@ enum DS9IORegisters {
 
 	DS9_REG_MAX = 0x106E,
 
-	DS9_REG_POSTFLG = 0x300,
 	DS9_REG_POWCNT1 = 0x304,
 };
 
diff --git a/src/ds/io.c b/src/ds/io.c
index 0f79eb6f9..6ccd0ea97 100644
--- a/src/ds/io.c
+++ b/src/ds/io.c
@@ -166,6 +166,7 @@ static void DSIOUpdateTimer(struct DSCommon* dscore, uint32_t address) {
 void DS7IOInit(struct DS* ds) {
 	memset(ds->memory.io7, 0, sizeof(ds->memory.io7));
 	ds->memory.io7[DS_REG_IPCFIFOCNT >> 1] = 0x0101;
+	ds->memory.io7[DS_REG_POSTFLG >> 1] = 0x0001;
 }
 
 void DS7IOWrite(struct DS* ds, uint32_t address, uint16_t value) {
@@ -322,6 +323,7 @@ uint32_t DS7IORead32(struct DS* ds, uint32_t address) {
 void DS9IOInit(struct DS* ds) {
 	memset(ds->memory.io9, 0, sizeof(ds->memory.io9));
 	ds->memory.io9[DS_REG_IPCFIFOCNT >> 1] = 0x0101;
+	ds->memory.io9[DS_REG_POSTFLG >> 1] = 0x0001;
 }
 
 void DS9IOWrite(struct DS* ds, uint32_t address, uint16_t value) {