diff --git a/lib/SDL.zig b/lib/SDL.zig
index 401c50f..d669250 160000
--- a/lib/SDL.zig
+++ b/lib/SDL.zig
@@ -1 +1 @@
-Subproject commit 401c50ff3d0b83ad4bd89caf580ce1bd90fb5618
+Subproject commit d66925011971fbe221fc2a7f7cb4cd8c181d9ba3
diff --git a/lib/util/bitfield.zig b/lib/util/bitfield.zig
index 1124cd2..b9ca43e 100644
--- a/lib/util/bitfield.zig
+++ b/lib/util/bitfield.zig
@@ -14,7 +14,7 @@ fn PtrCastPreserveCV(comptime T: type, comptime PtrToT: type, comptime NewT: typ
 fn BitType(comptime FieldType: type, comptime ValueType: type, comptime shamt: usize) type {
     const self_bit: FieldType = (1 << shamt);
 
-    return struct {
+    return extern struct {
         bits: Bitfield(FieldType, shamt, 1),
 
         pub fn set(self: anytype) void {
@@ -63,7 +63,7 @@ pub fn Bitfield(comptime FieldType: type, comptime shamt: usize, comptime num_bi
 
     const ValueType = std.meta.Int(.unsigned, num_bits);
 
-    return struct {
+    return extern struct {
         dummy: FieldType,
 
         fn field(self: anytype) PtrCastPreserveCV(@This(), @TypeOf(self), FieldType) {
diff --git a/src/core/cpu.zig b/src/core/cpu.zig
index 319841a..7ef1014 100644
--- a/src/core/cpu.zig
+++ b/src/core/cpu.zig
@@ -12,7 +12,7 @@ const File = std.fs.File;
 
 // ARM Instructions
 pub const arm = struct {
-    pub const InstrFn = fn (*Arm7tdmi, *Bus, u32) void;
+    pub const InstrFn = *const fn (*Arm7tdmi, *Bus, u32) void;
     const lut: [0x1000]InstrFn = populate();
 
     const processing = @import("cpu/arm/data_processing.zig").dataProcessing;
@@ -110,7 +110,7 @@ pub const arm = struct {
 
 // THUMB Instructions
 pub const thumb = struct {
-    pub const InstrFn = fn (*Arm7tdmi, *Bus, u16) void;
+    pub const InstrFn = *const fn (*Arm7tdmi, *Bus, u16) void;
     const lut: [0x400]InstrFn = populate();
 
     const processing = @import("cpu/thumb/data_processing.zig");