diff --git a/src/compiler.bbb b/src/compiler.bbb
index 5ff19c1..6fe2fb7 100644
--- a/src/compiler.bbb
+++ b/src/compiler.bbb
@@ -1,3 +1,14 @@
+Arena = struct
+{
+    reserved_size: u64,
+    position: u64,
+    os_position: u64,
+    granularity: u64,
+    reserved: [32]u8,
+}
+
+minimum_position: u64 = #byte_size(Arena);
+
 [export] main = fn [cc(c)] () s32
 {
     return 0;
diff --git a/src/converter.zig b/src/converter.zig
index c58ad80..bf3fe58 100644
--- a/src/converter.zig
+++ b/src/converter.zig
@@ -2561,6 +2561,7 @@ const Converter = struct {
     };
 
     const Intrinsic = enum {
+        byte_size,
         cast,
         cast_to,
         extend,
@@ -2584,6 +2585,30 @@ const Converter = struct {
         converter.skip_space();
 
         switch (intrinsic_keyword) {
+            .byte_size => {
+                const ty = converter.parse_type(module);
+                converter.skip_space();
+                converter.expect_character(')');
+                const byte_size = ty.get_byte_size();
+                const destination_type = expected_type orelse converter.report_error();
+                if (destination_type.bb != .integer) {
+                    converter.report_error();
+                }
+                const value = module.values.add();
+                value.* = .{
+                    .llvm = destination_type.llvm.handle.to_integer().get_constant(byte_size, @intFromBool(false)).to_value(),
+                    .bb = .{
+                        .constant_integer = .{
+                            .value = byte_size,
+                            .signed = false,
+                        },
+                    },
+                    .type = destination_type,
+                    .lvalue = false,
+                    .dereference_to_assign = false,
+                };
+                return value;
+            },
             .cast => {
                 @trap();
             },
diff --git a/src/converter_test.zig b/src/converter_test.zig
index ff2a689..081683c 100644
--- a/src/converter_test.zig
+++ b/src/converter_test.zig
@@ -368,3 +368,7 @@ test "indirect_varargs" {
 test "varargs" {
     try invsrc(@src());
 }
+
+test "byte_size" {
+    try invsrc(@src());
+}
diff --git a/tests/byte_size.bbb b/tests/byte_size.bbb
new file mode 100644
index 0000000..a07d92f
--- /dev/null
+++ b/tests/byte_size.bbb
@@ -0,0 +1,6 @@
+[export] main = fn [cc(c)] () s32
+{
+    >a: s32 = #byte_size(s32);
+    >b: s32 = #byte_size(s32);
+    return a - b;
+}