diff --git a/emulators/genesis_plus_gx.yml b/emulators/genesis_plus_gx.yml
index f7b87bd7..042fc165 100644
--- a/emulators/genesis_plus_gx.yml
+++ b/emulators/genesis_plus_gx.yml
@@ -63,9 +63,9 @@ files:
   # -------------------------------------------------------
   - name: bios_U.sms
     system: sega-mastersystem
-    region: [north-america, europe]
+    region: [north-america, latin-america, europe, oceania]
     required: false
-    note: "Master System (NTSC-U) boot ROM. Snail maze game built in. REGION_USA is the default of sms_cart_region_detect for any export header outside the PAL CRC list, so European cartridges load it too (core/cart_hw/sms_cart.c:831-874)."
+    note: "Master System (NTSC-U) boot ROM. Snail maze game built in. REGION_USA is the default of sms_cart_region_detect for any export header outside the PAL CRC list, so European, Australian and Brazilian cartridges outside that list load it too (core/cart_hw/sms_cart.c:831-874)."
     source_ref: "source core/loadrom.c:511"
 
   - name: bios_E.sms
diff --git a/emulators/genesis_plus_gx_expanded.yml b/emulators/genesis_plus_gx_expanded.yml
index 6baed6b5..18e54e52 100644
--- a/emulators/genesis_plus_gx_expanded.yml
+++ b/emulators/genesis_plus_gx_expanded.yml
@@ -68,9 +68,9 @@ files:
 
   - name: bios_U.sms
     system: sega-mastersystem
-    region: [north-america, europe]
+    region: [north-america, latin-america, europe, oceania]
     required: false
-    note: "Master System (NTSC-U) boot ROM, loaded for REGION_USA when the bios option is on."
+    note: "Master System (NTSC-U) boot ROM, loaded for REGION_USA when the bios option is on. REGION_USA is the default of sms_cart_region_detect for any export header outside its CRC list, so European, Australian and Brazilian cartridges outside that list load it too (core/cart_hw/sms_cart.c:865-866)."
     source_ref: "source core/loadrom.c:510"
 
   - name: bios_E.sms
diff --git a/emulators/genesis_plus_gx_wide.yml b/emulators/genesis_plus_gx_wide.yml
index f97100fd..ae9d229b 100644
--- a/emulators/genesis_plus_gx_wide.yml
+++ b/emulators/genesis_plus_gx_wide.yml
@@ -49,9 +49,9 @@ files:
 
   - name: bios_U.sms
     system: sega-mastersystem
-    region: [north-america, europe]
+    region: [north-america, latin-america, europe, oceania]
     required: false
-    note: "REGION_USA is the default of sms_cart_region_detect for any export header outside the PAL CRC list, so European cartridges load it too (core/cart_hw/sms_cart.c:863-864)."
+    note: "REGION_USA is the default of sms_cart_region_detect for any export header outside the PAL CRC list, so European, Australian and Brazilian cartridges outside that list load it too (core/cart_hw/sms_cart.c:863-864)."
     source_ref: "source core/loadrom.c:512"
 
   - name: bios_E.sms
diff --git a/tests/test_region.py b/tests/test_region.py
index 0e54c0c9..0068e364 100644
--- a/tests/test_region.py
+++ b/tests/test_region.py
@@ -919,6 +919,10 @@ class RegionalRequestsKeepWhatTheCodeLoads(unittest.TestCase):
         ("bizhawk", ["north-america"], "DSi_Nand_USA.bin"),
         ("bizhawk", ["oceania"], "DSi_Nand_AUS.bin"),
         ("bizhawk", ["china", "japan"], "DSi_Nand_CHN.bin"),
+        ("genesis_plus_gx", ["australia", "japan"], "bios_U.sms"),
+        ("genesis_plus_gx", ["brazil", "japan"], "bios_U.sms"),
+        ("genesis_plus_gx_wide", ["australia", "japan"], "bios_U.sms"),
+        ("genesis_plus_gx_expanded", ["brazil", "japan"], "bios_U.sms"),
     )
 
     def test_each_request_keeps_its_file(self):