diff --git a/enums.c b/enums.c
index 2dcb714..354d975 100644
--- a/enums.c
+++ b/enums.c
@@ -46,9 +46,10 @@ void compile_enum_def(env_t *env, ast_t *ast)
         num_tags += 1;
 
     type_t *t = Table$str_get(*env->types, def->name);
-    CORD typeinfo = CORD_asprintf("public const TypeInfo_t %r = {%zu, %zu, .metamethods=Enum$metamethods, {.tag=EnumInfo, .EnumInfo={.name=\"%s\", "
+    const char *metamethods = is_packed_data(t) ? "PackedDataEnum$metamethods" : "Enum$metamethods";
+    CORD typeinfo = CORD_asprintf("public const TypeInfo_t %r = {%zu, %zu, .metamethods=%s, {.tag=EnumInfo, .EnumInfo={.name=\"%s\", "
                                   ".num_tags=%d, .tags=(NamedType_t[]){",
-                                  full_name, type_size(t), type_align(t), def->name, num_tags);
+                                  full_name, type_size(t), type_align(t), metamethods, def->name, num_tags);
 
     for (tag_ast_t *tag = def->tags; tag; tag = tag->next) {
         const char *tag_type_name = heap_strf("%s$%s", def->name, tag->name);
diff --git a/stdlib/enums.h b/stdlib/enums.h
index 35c3a22..a61daac 100644
--- a/stdlib/enums.h
+++ b/stdlib/enums.h
@@ -25,4 +25,14 @@ void Enum$deserialize(FILE *in, void *outval, Array_t *pointers, const TypeInfo_
     .deserialize=Enum$deserialize, \
 })
 
+#define PackedDataEnum$metamethods ((metamethods_t){ \
+    .hash=PackedData$hash, \
+    .compare=Enum$compare, \
+    .equal=PackedData$equal, \
+    .as_text=Enum$as_text, \
+    .is_none=Enum$is_none, \
+    .serialize=Enum$serialize, \
+    .deserialize=Enum$deserialize, \
+})
+
 // vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1,\:0
diff --git a/stdlib/structs.c b/stdlib/structs.c
index 010b49f..1ff5a91 100644
--- a/stdlib/structs.c
+++ b/stdlib/structs.c
@@ -53,6 +53,14 @@ PUREFUNC public uint64_t Struct$hash(const void *obj, const TypeInfo_t *type)
 }
 #pragma GCC diagnostic pop
 
+PUREFUNC public uint64_t PackedData$hash(const void *obj, const TypeInfo_t *type)
+{
+    if (type->StructInfo.num_fields == 0)
+        return 0;
+
+    return siphash24(obj, (size_t)type->size);
+}
+
 PUREFUNC public int32_t Struct$compare(const void *x, const void *y, const TypeInfo_t *type)
 {
     if (x == y)
@@ -122,6 +130,12 @@ PUREFUNC public bool Struct$equal(const void *x, const void *y, const TypeInfo_t
     return true;
 }
 
+PUREFUNC public bool PackedData$equal(const void *x, const void *y, const TypeInfo_t *type)
+{
+    if (x == y) return true;
+    return (memcmp(x, y, (size_t)type->size) == 0);
+}
+
 PUREFUNC public Text_t Struct$as_text(const void *obj, bool colorize, const TypeInfo_t *type)
 {
     if (!obj) return Text$from_str(type->StructInfo.name);
diff --git a/stdlib/structs.h b/stdlib/structs.h
index 6553cc8..b027a01 100644
--- a/stdlib/structs.h
+++ b/stdlib/structs.h
@@ -8,8 +8,10 @@
 #include "util.h"
 
 PUREFUNC uint64_t Struct$hash(const void *obj, const TypeInfo_t *type);
+PUREFUNC uint64_t PackedData$hash(const void *obj, const TypeInfo_t *type);
 PUREFUNC int32_t Struct$compare(const void *x, const void *y, const TypeInfo_t *type);
 PUREFUNC bool Struct$equal(const void *x, const void *y, const TypeInfo_t *type);
+PUREFUNC bool PackedData$equal(const void *x, const void *y, const TypeInfo_t *type);
 PUREFUNC Text_t Struct$as_text(const void *obj, bool colorize, const TypeInfo_t *type);
 PUREFUNC bool Struct$is_none(const void *obj, const TypeInfo_t *type);
 void Struct$serialize(const void *obj, FILE *out, Table_t *pointers, const TypeInfo_t *type);
@@ -25,4 +27,14 @@ void Struct$deserialize(FILE *in, void *outval, Array_t *pointers, const TypeInf
     .deserialize=Struct$deserialize, \
 })
 
+#define PackedData$metamethods ((metamethods_t){ \
+    .hash=PackedData$hash, \
+    .compare=Struct$compare, \
+    .equal=PackedData$equal, \
+    .as_text=Struct$as_text, \
+    .is_none=Struct$is_none, \
+    .serialize=Struct$serialize, \
+    .deserialize=Struct$deserialize, \
+})
+
 // vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1,\:0
diff --git a/structs.c b/structs.c
index ce5116e..8e18426 100644
--- a/structs.c
+++ b/structs.c
@@ -27,10 +27,11 @@ void compile_struct_def(env_t *env, ast_t *ast)
         short_name = strrchr(short_name, '$') + 1;
 
     env->code->typeinfos = CORD_all("public const TypeInfo_t ", full_name, ";\n", env->code->typeinfos);
-    CORD typeinfo = CORD_asprintf("public const TypeInfo_t %r = {.size=%zu, .align=%zu, .metamethods=Struct$metamethods, "
+    const char *metamethods = is_packed_data(t) ? "PackedData$metamethods" : "Struct$metamethods";
+    CORD typeinfo = CORD_asprintf("public const TypeInfo_t %r = {.size=%zu, .align=%zu, .metamethods=%s, "
                                   ".tag=StructInfo, .StructInfo.name=\"%s\"%s, "
                                   ".StructInfo.num_fields=%ld",
-                                  full_name, type_size(t), type_align(t), short_name, def->secret ? ", .StructInfo.is_secret=true" : "",
+                                  full_name, type_size(t), type_align(t), metamethods, short_name, def->secret ? ", .StructInfo.is_secret=true" : "",
                                   num_fields);
     if (def->fields) {
         typeinfo = CORD_asprintf("%r, .StructInfo.fields=(NamedType_t[%d]){", typeinfo, num_fields);
diff --git a/types.c b/types.c
index 2b421b4..5c37a68 100644
--- a/types.c
+++ b/types.c
@@ -444,21 +444,55 @@ PUREFUNC bool is_numeric_type(type_t *t)
     return t->tag == IntType || t->tag == BigIntType || t->tag == NumType || t->tag == ByteType;
 }
 
+PUREFUNC bool is_packed_data(type_t *t)
+{
+    if (t->tag == IntType || t->tag == NumType || t->tag == ByteType || t->tag == PointerType || t->tag == BoolType || t->tag == FunctionType) {
+        return true;
+    } else if (t->tag == StructType) {
+        for (arg_t *field = Match(t, StructType)->fields; field; field = field->next) {
+            if (!is_packed_data(field->type))
+                return false;
+        }
+        return true;
+    } else if (t->tag == EnumType) {
+        for (tag_t *tag = Match(t, EnumType)->tags; tag; tag = tag->next) {
+            if (!is_packed_data(tag->type))
+                return false;
+        }
+        return true;
+    } else {
+        return false;
+    }
+}
+
 PUREFUNC size_t unpadded_struct_size(type_t *t)
 {
     arg_t *fields = Match(t, StructType)->fields;
     size_t size = 0;
+    size_t bit_offset = 0;
     for (arg_t *field = fields; field; field = field->next) {
         type_t *field_type = field->type;
         if (field_type->tag == BoolType) {
-            size += 1; // Bit packing
+            bit_offset += 1;
+            if (bit_offset >= 8) {
+                size += 1;
+                bit_offset = 0;
+            }
         } else {
+            if (bit_offset > 0) {
+                size += 1;
+                bit_offset = 0;
+            }
             size_t align = type_align(field_type);
             if (align > 1 && size % align > 0)
                 size += align - (size % align); // Padding
             size += type_size(field_type);
         }
     }
+    if (bit_offset > 0) {
+        size += 1;
+        bit_offset = 0;
+    }
     return size;
 }
 
diff --git a/types.h b/types.h
index 0163c4d..2909883 100644
--- a/types.h
+++ b/types.h
@@ -150,6 +150,7 @@ PUREFUNC bool can_promote(type_t *actual, type_t *needed);
 PUREFUNC const char *enum_single_value_tag(type_t *enum_type, type_t *t);
 PUREFUNC bool is_int_type(type_t *t);
 PUREFUNC bool is_numeric_type(type_t *t);
+PUREFUNC bool is_packed_data(type_t *t);
 PUREFUNC size_t type_size(type_t *t);
 PUREFUNC size_t type_align(type_t *t);
 PUREFUNC size_t unpadded_struct_size(type_t *t);