diff --git a/src/bus/Bios.zig b/src/bus/Bios.zig
index ec00bec..489ee2b 100644
--- a/src/bus/Bios.zig
+++ b/src/bus/Bios.zig
@@ -29,6 +29,11 @@ pub fn deinit(self: Self) void {
 
 pub fn read(self: *const Self, comptime T: type, addr: usize) T {
     if (self.buf) |buf| {
+        if (addr > buf.len) {
+            log.err("Tried to read {} from {X:0>8} (open bus)", .{ T, addr });
+            return 0;
+        }
+
         return switch (T) {
             u32 => (@as(u32, buf[addr + 3]) << 24) | (@as(u32, buf[addr + 2]) << 16) | (@as(u32, buf[addr + 1]) << 8) | (@as(u32, buf[addr])),
             u16 => (@as(u16, buf[addr + 1]) << 8) | @as(u16, buf[addr]),