diff --git a/CHANGES b/CHANGES
index 17769d465..0397d71f7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,7 @@ Emulation fixes:
 Other fixes:
  - Core: Fix ELF loading regression (fixes mgba.io/i/1669)
  - Core: Fix crash modifying hash table entry (fixes mgba.io/i/1673)
+ - GBA: Reject incorrectly sized BIOSes
  - Qt: Fix OpenGL 2.1 support (fixes mgba.io/i/1678)
 Misc:
  - Qt: Disable Replace ROM option when no game loaded
diff --git a/src/gba/gba.c b/src/gba/gba.c
index 769e85ba0..c399ac57c 100644
--- a/src/gba/gba.c
+++ b/src/gba/gba.c
@@ -445,6 +445,10 @@ void GBAYankROM(struct GBA* gba) {
 
 void GBALoadBIOS(struct GBA* gba, struct VFile* vf) {
 	gba->biosVf = vf;
+	if (vf->size(vf) != SIZE_BIOS) {
+		mLOG(GBA, WARN, "Incorrect BIOS size");
+		return;
+	}
 	uint32_t* bios = vf->map(vf, SIZE_BIOS, MAP_READ);
 	if (!bios) {
 		mLOG(GBA, WARN, "Couldn't map BIOS");