diff --git a/src/bindgen/ir/enumeration.rs b/src/bindgen/ir/enumeration.rs
index 71d0c0eb..960862f1 100644
--- a/src/bindgen/ir/enumeration.rs
+++ b/src/bindgen/ir/enumeration.rs
@@ -682,7 +682,8 @@ impl Source for Enum {
                 out.open_brace();
             }
 
-            if config.language == Language::C && !config.style.generate_typedef() {
+            if config.language == Language::C && !size.is_some() && !config.style.generate_typedef()
+            {
                 out.write("enum ");
             }
 
diff --git a/tests/expectations/both/enum.c b/tests/expectations/both/enum.c
index 365439e2..0a2a2029 100644
--- a/tests/expectations/both/enum.c
+++ b/tests/expectations/both/enum.c
@@ -157,6 +157,30 @@ typedef struct I {
   };
 } I;
 
+enum P_Tag {
+  P0,
+  P1,
+};
+typedef uint8_t P_Tag;
+
+typedef struct P0_Body {
+  uint8_t _0;
+} P0_Body;
+
+typedef struct P1_Body {
+  uint8_t _0;
+  uint8_t _1;
+  uint8_t _2;
+} P1_Body;
+
+typedef struct P {
+  P_Tag tag;
+  union {
+    P0_Body p0;
+    P1_Body p1;
+  };
+} P;
+
 void root(Opaque *opaque,
           A a,
           B b,
@@ -172,4 +196,12 @@ void root(Opaque *opaque,
           L l,
           M m,
           N n,
-          O o);
+          O o,
+          P p);
+
+#include <stddef.h>
+#include "testing-helpers.h"
+static_assert(offsetof(CBINDGEN_STRUCT(P), tag) == 0, "unexpected offset for tag");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p0");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p1");
+static_assert(sizeof(CBINDGEN_STRUCT(P)) == 4, "unexpected size for P");
diff --git a/tests/expectations/both/enum.compat.c b/tests/expectations/both/enum.compat.c
index f899fd69..5b93c765 100644
--- a/tests/expectations/both/enum.compat.c
+++ b/tests/expectations/both/enum.compat.c
@@ -217,6 +217,36 @@ typedef struct I {
   };
 } I;
 
+enum P_Tag
+#ifdef __cplusplus
+  : uint8_t
+#endif // __cplusplus
+ {
+  P0,
+  P1,
+};
+#ifndef __cplusplus
+typedef uint8_t P_Tag;
+#endif // __cplusplus
+
+typedef struct P0_Body {
+  uint8_t _0;
+} P0_Body;
+
+typedef struct P1_Body {
+  uint8_t _0;
+  uint8_t _1;
+  uint8_t _2;
+} P1_Body;
+
+typedef struct P {
+  P_Tag tag;
+  union {
+    P0_Body p0;
+    P1_Body p1;
+  };
+} P;
+
 #ifdef __cplusplus
 extern "C" {
 #endif // __cplusplus
@@ -236,8 +266,16 @@ void root(Opaque *opaque,
           L l,
           M m,
           N n,
-          O o);
+          O o,
+          P p);
 
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus
+
+#include <stddef.h>
+#include "testing-helpers.h"
+static_assert(offsetof(CBINDGEN_STRUCT(P), tag) == 0, "unexpected offset for tag");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p0");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p1");
+static_assert(sizeof(CBINDGEN_STRUCT(P)) == 4, "unexpected size for P");
diff --git a/tests/expectations/enum.c b/tests/expectations/enum.c
index 48eb9345..2cb8fac0 100644
--- a/tests/expectations/enum.c
+++ b/tests/expectations/enum.c
@@ -157,6 +157,30 @@ typedef struct {
   };
 } I;
 
+enum P_Tag {
+  P0,
+  P1,
+};
+typedef uint8_t P_Tag;
+
+typedef struct {
+  uint8_t _0;
+} P0_Body;
+
+typedef struct {
+  uint8_t _0;
+  uint8_t _1;
+  uint8_t _2;
+} P1_Body;
+
+typedef struct {
+  P_Tag tag;
+  union {
+    P0_Body p0;
+    P1_Body p1;
+  };
+} P;
+
 void root(Opaque *opaque,
           A a,
           B b,
@@ -172,4 +196,12 @@ void root(Opaque *opaque,
           L l,
           M m,
           N n,
-          O o);
+          O o,
+          P p);
+
+#include <stddef.h>
+#include "testing-helpers.h"
+static_assert(offsetof(CBINDGEN_STRUCT(P), tag) == 0, "unexpected offset for tag");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p0");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p1");
+static_assert(sizeof(CBINDGEN_STRUCT(P)) == 4, "unexpected size for P");
diff --git a/tests/expectations/enum.compat.c b/tests/expectations/enum.compat.c
index 2025a258..075f27ee 100644
--- a/tests/expectations/enum.compat.c
+++ b/tests/expectations/enum.compat.c
@@ -217,6 +217,36 @@ typedef struct {
   };
 } I;
 
+enum P_Tag
+#ifdef __cplusplus
+  : uint8_t
+#endif // __cplusplus
+ {
+  P0,
+  P1,
+};
+#ifndef __cplusplus
+typedef uint8_t P_Tag;
+#endif // __cplusplus
+
+typedef struct {
+  uint8_t _0;
+} P0_Body;
+
+typedef struct {
+  uint8_t _0;
+  uint8_t _1;
+  uint8_t _2;
+} P1_Body;
+
+typedef struct {
+  P_Tag tag;
+  union {
+    P0_Body p0;
+    P1_Body p1;
+  };
+} P;
+
 #ifdef __cplusplus
 extern "C" {
 #endif // __cplusplus
@@ -236,8 +266,16 @@ void root(Opaque *opaque,
           L l,
           M m,
           N n,
-          O o);
+          O o,
+          P p);
 
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus
+
+#include <stddef.h>
+#include "testing-helpers.h"
+static_assert(offsetof(CBINDGEN_STRUCT(P), tag) == 0, "unexpected offset for tag");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p0");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p1");
+static_assert(sizeof(CBINDGEN_STRUCT(P)) == 4, "unexpected size for P");
diff --git a/tests/expectations/enum.cpp b/tests/expectations/enum.cpp
index d39fa56e..6a63e6c6 100644
--- a/tests/expectations/enum.cpp
+++ b/tests/expectations/enum.cpp
@@ -149,6 +149,29 @@ struct I {
   };
 };
 
+struct P {
+  enum class Tag : uint8_t {
+    P0,
+    P1,
+  };
+
+  struct P0_Body {
+    uint8_t _0;
+  };
+
+  struct P1_Body {
+    uint8_t _0;
+    uint8_t _1;
+    uint8_t _2;
+  };
+
+  Tag tag;
+  union {
+    P0_Body p0;
+    P1_Body p1;
+  };
+};
+
 extern "C" {
 
 void root(Opaque *opaque,
@@ -166,6 +189,14 @@ void root(Opaque *opaque,
           L l,
           M m,
           N n,
-          O o);
+          O o,
+          P p);
 
 } // extern "C"
+
+#include <stddef.h>
+#include "testing-helpers.h"
+static_assert(offsetof(CBINDGEN_STRUCT(P), tag) == 0, "unexpected offset for tag");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p0");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p1");
+static_assert(sizeof(CBINDGEN_STRUCT(P)) == 4, "unexpected size for P");
diff --git a/tests/expectations/tag/annotation.c b/tests/expectations/tag/annotation.c
index e567839c..6c75c0f5 100644
--- a/tests/expectations/tag/annotation.c
+++ b/tests/expectations/tag/annotation.c
@@ -37,7 +37,7 @@ struct Bar_Body {
 };
 
 union F {
-  enum F_Tag tag;
+  F_Tag tag;
   struct Foo_Body foo;
   struct Bar_Body bar;
 };
@@ -59,7 +59,7 @@ struct There_Body {
 };
 
 struct H {
-  enum H_Tag tag;
+  H_Tag tag;
   union {
     struct Hello_Body hello;
     struct There_Body there;
diff --git a/tests/expectations/tag/annotation.compat.c b/tests/expectations/tag/annotation.compat.c
index 37972665..3741d678 100644
--- a/tests/expectations/tag/annotation.compat.c
+++ b/tests/expectations/tag/annotation.compat.c
@@ -49,7 +49,7 @@ struct Bar_Body {
 };
 
 union F {
-  enum F_Tag tag;
+  F_Tag tag;
   struct Foo_Body foo;
   struct Bar_Body bar;
 };
@@ -77,7 +77,7 @@ struct There_Body {
 };
 
 struct H {
-  enum H_Tag tag;
+  H_Tag tag;
   union {
     struct Hello_Body hello;
     struct There_Body there;
diff --git a/tests/expectations/tag/asserted-cast.c b/tests/expectations/tag/asserted-cast.c
index 3d63ca89..5ef7f94c 100644
--- a/tests/expectations/tag/asserted-cast.c
+++ b/tests/expectations/tag/asserted-cast.c
@@ -25,7 +25,7 @@ struct H_Bar_Body {
 };
 
 struct H {
-  enum H_Tag tag;
+  H_Tag tag;
   union {
     struct H_Foo_Body foo;
     struct H_Bar_Body bar;
@@ -49,7 +49,7 @@ struct J_Bar_Body {
 };
 
 struct J {
-  enum J_Tag tag;
+  J_Tag tag;
   union {
     struct J_Foo_Body foo;
     struct J_Bar_Body bar;
@@ -75,7 +75,7 @@ struct K_Bar_Body {
 };
 
 union K {
-  enum K_Tag tag;
+  K_Tag tag;
   struct K_Foo_Body foo;
   struct K_Bar_Body bar;
 };
diff --git a/tests/expectations/tag/asserted-cast.compat.c b/tests/expectations/tag/asserted-cast.compat.c
index 490054ae..98dccafb 100644
--- a/tests/expectations/tag/asserted-cast.compat.c
+++ b/tests/expectations/tag/asserted-cast.compat.c
@@ -31,7 +31,7 @@ struct H_Bar_Body {
 };
 
 struct H {
-  enum H_Tag tag;
+  H_Tag tag;
   union {
     struct H_Foo_Body foo;
     struct H_Bar_Body bar;
@@ -61,7 +61,7 @@ struct J_Bar_Body {
 };
 
 struct J {
-  enum J_Tag tag;
+  J_Tag tag;
   union {
     struct J_Foo_Body foo;
     struct J_Bar_Body bar;
@@ -93,7 +93,7 @@ struct K_Bar_Body {
 };
 
 union K {
-  enum K_Tag tag;
+  K_Tag tag;
   struct K_Foo_Body foo;
   struct K_Bar_Body bar;
 };
diff --git a/tests/expectations/tag/derive-eq.c b/tests/expectations/tag/derive-eq.c
index b64b36c2..4de1da99 100644
--- a/tests/expectations/tag/derive-eq.c
+++ b/tests/expectations/tag/derive-eq.c
@@ -34,7 +34,7 @@ struct FooParen_Body {
 };
 
 union Bar {
-  enum Bar_Tag tag;
+  Bar_Tag tag;
   struct Bazz_Body bazz;
   struct FooNamed_Body foo_named;
   struct FooParen_Body foo_paren;
diff --git a/tests/expectations/tag/derive-eq.compat.c b/tests/expectations/tag/derive-eq.compat.c
index 25d2b0fc..4e99d1c2 100644
--- a/tests/expectations/tag/derive-eq.compat.c
+++ b/tests/expectations/tag/derive-eq.compat.c
@@ -40,7 +40,7 @@ struct FooParen_Body {
 };
 
 union Bar {
-  enum Bar_Tag tag;
+  Bar_Tag tag;
   struct Bazz_Body bazz;
   struct FooNamed_Body foo_named;
   struct FooParen_Body foo_paren;
diff --git a/tests/expectations/tag/destructor-and-copy-ctor.c b/tests/expectations/tag/destructor-and-copy-ctor.c
index b28a3ab3..8b47895d 100644
--- a/tests/expectations/tag/destructor-and-copy-ctor.c
+++ b/tests/expectations/tag/destructor-and-copy-ctor.c
@@ -65,7 +65,7 @@ struct Slice4_Body_u32 {
 };
 
 struct Foo_u32 {
-  enum Foo_u32_Tag tag;
+  Foo_u32_Tag tag;
   union {
     struct Polygon1_Body_u32 polygon1;
     struct Slice1_Body_u32 slice1;
@@ -118,7 +118,7 @@ struct Slice24_Body_i32 {
 };
 
 union Baz_i32 {
-  enum Baz_i32_Tag tag;
+  Baz_i32_Tag tag;
   struct Polygon21_Body_i32 polygon21;
   struct Slice21_Body_i32 slice21;
   struct Slice22_Body_i32 slice22;
@@ -144,7 +144,7 @@ struct Taz3_Body {
 };
 
 union Taz {
-  enum Taz_Tag tag;
+  Taz_Tag tag;
   struct Taz1_Body taz1;
   struct Taz3_Body taz3;
 };
@@ -161,7 +161,7 @@ struct Taz2_Body {
 };
 
 union Tazz {
-  enum Tazz_Tag tag;
+  Tazz_Tag tag;
   struct Taz2_Body taz2;
 };
 
diff --git a/tests/expectations/tag/destructor-and-copy-ctor.compat.c b/tests/expectations/tag/destructor-and-copy-ctor.compat.c
index 98723845..700b8a1d 100644
--- a/tests/expectations/tag/destructor-and-copy-ctor.compat.c
+++ b/tests/expectations/tag/destructor-and-copy-ctor.compat.c
@@ -77,7 +77,7 @@ struct Slice4_Body_u32 {
 };
 
 struct Foo_u32 {
-  enum Foo_u32_Tag tag;
+  Foo_u32_Tag tag;
   union {
     struct Polygon1_Body_u32 polygon1;
     struct Slice1_Body_u32 slice1;
@@ -136,7 +136,7 @@ struct Slice24_Body_i32 {
 };
 
 union Baz_i32 {
-  enum Baz_i32_Tag tag;
+  Baz_i32_Tag tag;
   struct Polygon21_Body_i32 polygon21;
   struct Slice21_Body_i32 slice21;
   struct Slice22_Body_i32 slice22;
@@ -168,7 +168,7 @@ struct Taz3_Body {
 };
 
 union Taz {
-  enum Taz_Tag tag;
+  Taz_Tag tag;
   struct Taz1_Body taz1;
   struct Taz3_Body taz3;
 };
@@ -191,7 +191,7 @@ struct Taz2_Body {
 };
 
 union Tazz {
-  enum Tazz_Tag tag;
+  Tazz_Tag tag;
   struct Taz2_Body taz2;
 };
 
diff --git a/tests/expectations/tag/display_list.c b/tests/expectations/tag/display_list.c
index bb843e6c..78f53de3 100644
--- a/tests/expectations/tag/display_list.c
+++ b/tests/expectations/tag/display_list.c
@@ -37,7 +37,7 @@ struct Image_Body {
 };
 
 union DisplayItem {
-  enum DisplayItem_Tag tag;
+  DisplayItem_Tag tag;
   struct Fill_Body fill;
   struct Image_Body image;
 };
diff --git a/tests/expectations/tag/display_list.compat.c b/tests/expectations/tag/display_list.compat.c
index 91318db8..86f91657 100644
--- a/tests/expectations/tag/display_list.compat.c
+++ b/tests/expectations/tag/display_list.compat.c
@@ -43,7 +43,7 @@ struct Image_Body {
 };
 
 union DisplayItem {
-  enum DisplayItem_Tag tag;
+  DisplayItem_Tag tag;
   struct Fill_Body fill;
   struct Image_Body image;
 };
diff --git a/tests/expectations/tag/enum.c b/tests/expectations/tag/enum.c
index d98f505e..03d59f28 100644
--- a/tests/expectations/tag/enum.c
+++ b/tests/expectations/tag/enum.c
@@ -105,7 +105,7 @@ struct Bar_Body {
 };
 
 union G {
-  enum G_Tag tag;
+  G_Tag tag;
   struct Foo_Body foo;
   struct Bar_Body bar;
 };
@@ -150,13 +150,37 @@ struct I_Bar_Body {
 };
 
 struct I {
-  enum I_Tag tag;
+  I_Tag tag;
   union {
     struct I_Foo_Body foo;
     struct I_Bar_Body bar;
   };
 };
 
+enum P_Tag {
+  P0,
+  P1,
+};
+typedef uint8_t P_Tag;
+
+struct P0_Body {
+  uint8_t _0;
+};
+
+struct P1_Body {
+  uint8_t _0;
+  uint8_t _1;
+  uint8_t _2;
+};
+
+struct P {
+  P_Tag tag;
+  union {
+    struct P0_Body p0;
+    struct P1_Body p1;
+  };
+};
+
 void root(struct Opaque *opaque,
           A a,
           B b,
@@ -172,4 +196,12 @@ void root(struct Opaque *opaque,
           enum L l,
           M m,
           enum N n,
-          O o);
+          O o,
+          struct P p);
+
+#include <stddef.h>
+#include "testing-helpers.h"
+static_assert(offsetof(CBINDGEN_STRUCT(P), tag) == 0, "unexpected offset for tag");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p0");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p1");
+static_assert(sizeof(CBINDGEN_STRUCT(P)) == 4, "unexpected size for P");
diff --git a/tests/expectations/tag/enum.compat.c b/tests/expectations/tag/enum.compat.c
index 7b2e4260..21aafa33 100644
--- a/tests/expectations/tag/enum.compat.c
+++ b/tests/expectations/tag/enum.compat.c
@@ -159,7 +159,7 @@ struct Bar_Body {
 };
 
 union G {
-  enum G_Tag tag;
+  G_Tag tag;
   struct Foo_Body foo;
   struct Bar_Body bar;
 };
@@ -210,13 +210,43 @@ struct I_Bar_Body {
 };
 
 struct I {
-  enum I_Tag tag;
+  I_Tag tag;
   union {
     struct I_Foo_Body foo;
     struct I_Bar_Body bar;
   };
 };
 
+enum P_Tag
+#ifdef __cplusplus
+  : uint8_t
+#endif // __cplusplus
+ {
+  P0,
+  P1,
+};
+#ifndef __cplusplus
+typedef uint8_t P_Tag;
+#endif // __cplusplus
+
+struct P0_Body {
+  uint8_t _0;
+};
+
+struct P1_Body {
+  uint8_t _0;
+  uint8_t _1;
+  uint8_t _2;
+};
+
+struct P {
+  P_Tag tag;
+  union {
+    struct P0_Body p0;
+    struct P1_Body p1;
+  };
+};
+
 #ifdef __cplusplus
 extern "C" {
 #endif // __cplusplus
@@ -236,8 +266,16 @@ void root(struct Opaque *opaque,
           enum L l,
           M m,
           enum N n,
-          O o);
+          O o,
+          struct P p);
 
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus
+
+#include <stddef.h>
+#include "testing-helpers.h"
+static_assert(offsetof(CBINDGEN_STRUCT(P), tag) == 0, "unexpected offset for tag");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p0");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p1");
+static_assert(sizeof(CBINDGEN_STRUCT(P)) == 4, "unexpected size for P");
diff --git a/tests/expectations/tag/enum_self.c b/tests/expectations/tag/enum_self.c
index bddae4ae..66476f0d 100644
--- a/tests/expectations/tag/enum_self.c
+++ b/tests/expectations/tag/enum_self.c
@@ -25,7 +25,7 @@ struct Max_Body {
 };
 
 union Bar {
-  enum Bar_Tag tag;
+  Bar_Tag tag;
   struct Min_Body min;
   struct Max_Body max;
 };
diff --git a/tests/expectations/tag/enum_self.compat.c b/tests/expectations/tag/enum_self.compat.c
index 608f701e..53bb9ab7 100644
--- a/tests/expectations/tag/enum_self.compat.c
+++ b/tests/expectations/tag/enum_self.compat.c
@@ -31,7 +31,7 @@ struct Max_Body {
 };
 
 union Bar {
-  enum Bar_Tag tag;
+  Bar_Tag tag;
   struct Min_Body min;
   struct Max_Body max;
 };
diff --git a/tests/expectations/tag/must-use.c b/tests/expectations/tag/must-use.c
index 04452231..55df7c49 100644
--- a/tests/expectations/tag/must-use.c
+++ b/tests/expectations/tag/must-use.c
@@ -19,7 +19,7 @@ struct Owned_Body_i32 {
 };
 
 struct MaybeOwnedPtr_i32 {
-  enum MaybeOwnedPtr_i32_Tag tag;
+  MaybeOwnedPtr_i32_Tag tag;
   union {
     struct Owned_Body_i32 owned;
   };
diff --git a/tests/expectations/tag/must-use.compat.c b/tests/expectations/tag/must-use.compat.c
index 69fe2796..9bf8bf05 100644
--- a/tests/expectations/tag/must-use.compat.c
+++ b/tests/expectations/tag/must-use.compat.c
@@ -25,7 +25,7 @@ struct Owned_Body_i32 {
 };
 
 struct MaybeOwnedPtr_i32 {
-  enum MaybeOwnedPtr_i32_Tag tag;
+  MaybeOwnedPtr_i32_Tag tag;
   union {
     struct Owned_Body_i32 owned;
   };
diff --git a/tests/expectations/tag/prefix.c b/tests/expectations/tag/prefix.c
index 6f6d1035..005f062f 100644
--- a/tests/expectations/tag/prefix.c
+++ b/tests/expectations/tag/prefix.c
@@ -26,7 +26,7 @@ struct PREFIX_Weight_Body {
 };
 
 union PREFIX_AbsoluteFontWeight {
-  enum PREFIX_AbsoluteFontWeight_Tag tag;
+  PREFIX_AbsoluteFontWeight_Tag tag;
   struct PREFIX_Weight_Body weight;
 };
 
diff --git a/tests/expectations/tag/prefix.compat.c b/tests/expectations/tag/prefix.compat.c
index a6ad2cec..52069c43 100644
--- a/tests/expectations/tag/prefix.compat.c
+++ b/tests/expectations/tag/prefix.compat.c
@@ -32,7 +32,7 @@ struct PREFIX_Weight_Body {
 };
 
 union PREFIX_AbsoluteFontWeight {
-  enum PREFIX_AbsoluteFontWeight_Tag tag;
+  PREFIX_AbsoluteFontWeight_Tag tag;
   struct PREFIX_Weight_Body weight;
 };
 
diff --git a/tests/expectations/tag/reserved.c b/tests/expectations/tag/reserved.c
index 97cb7103..0e8af58d 100644
--- a/tests/expectations/tag/reserved.c
+++ b/tests/expectations/tag/reserved.c
@@ -24,7 +24,7 @@ struct D_Body {
 };
 
 struct C {
-  enum C_Tag tag;
+  C_Tag tag;
   union {
     struct D_Body d;
   };
diff --git a/tests/expectations/tag/reserved.compat.c b/tests/expectations/tag/reserved.compat.c
index 33033c53..39e4e805 100644
--- a/tests/expectations/tag/reserved.compat.c
+++ b/tests/expectations/tag/reserved.compat.c
@@ -30,7 +30,7 @@ struct D_Body {
 };
 
 struct C {
-  enum C_Tag tag;
+  C_Tag tag;
   union {
     struct D_Body d;
   };
diff --git a/tests/expectations/tag/sentinel.c b/tests/expectations/tag/sentinel.c
index 684eeb3e..8e376e63 100644
--- a/tests/expectations/tag/sentinel.c
+++ b/tests/expectations/tag/sentinel.c
@@ -47,7 +47,7 @@ struct C_C2_Body {
 };
 
 union C {
-  enum C_Tag tag;
+  C_Tag tag;
   struct C_C1_Body c1;
   struct C_C2_Body c2;
 };
diff --git a/tests/expectations/tag/sentinel.compat.c b/tests/expectations/tag/sentinel.compat.c
index 828bbcc4..ae7f94c4 100644
--- a/tests/expectations/tag/sentinel.compat.c
+++ b/tests/expectations/tag/sentinel.compat.c
@@ -65,7 +65,7 @@ struct C_C2_Body {
 };
 
 union C {
-  enum C_Tag tag;
+  C_Tag tag;
   struct C_C1_Body c1;
   struct C_C2_Body c2;
 };
diff --git a/tests/expectations/tag/transform-op.c b/tests/expectations/tag/transform-op.c
index 023f3f21..f738fd3e 100644
--- a/tests/expectations/tag/transform-op.c
+++ b/tests/expectations/tag/transform-op.c
@@ -39,7 +39,7 @@ struct StyleBaz_Body_i32 {
 };
 
 union StyleFoo_i32 {
-  enum StyleFoo_i32_Tag tag;
+  StyleFoo_i32_Tag tag;
   struct StyleFoo_Body_i32 foo;
   struct StyleBar_Body_i32 bar;
   struct StyleBaz_Body_i32 baz;
@@ -130,7 +130,7 @@ struct StyleBaz2_Body {
 };
 
 union StyleBaz {
-  enum StyleBaz_Tag tag;
+  StyleBaz_Tag tag;
   struct StyleBaz1_Body baz1;
   struct StyleBaz2_Body baz2;
 };
@@ -151,7 +151,7 @@ struct StyleTaz2_Body {
 };
 
 struct StyleTaz {
-  enum StyleTaz_Tag tag;
+  StyleTaz_Tag tag;
   union {
     struct StyleTaz1_Body taz1;
     struct StyleTaz2_Body taz2;
diff --git a/tests/expectations/tag/transform-op.compat.c b/tests/expectations/tag/transform-op.compat.c
index 79ed9c31..eb236c35 100644
--- a/tests/expectations/tag/transform-op.compat.c
+++ b/tests/expectations/tag/transform-op.compat.c
@@ -45,7 +45,7 @@ struct StyleBaz_Body_i32 {
 };
 
 union StyleFoo_i32 {
-  enum StyleFoo_i32_Tag tag;
+  StyleFoo_i32_Tag tag;
   struct StyleFoo_Body_i32 foo;
   struct StyleBar_Body_i32 bar;
   struct StyleBaz_Body_i32 baz;
@@ -142,7 +142,7 @@ struct StyleBaz2_Body {
 };
 
 union StyleBaz {
-  enum StyleBaz_Tag tag;
+  StyleBaz_Tag tag;
   struct StyleBaz1_Body baz1;
   struct StyleBaz2_Body baz2;
 };
@@ -169,7 +169,7 @@ struct StyleTaz2_Body {
 };
 
 struct StyleTaz {
-  enum StyleTaz_Tag tag;
+  StyleTaz_Tag tag;
   union {
     struct StyleTaz1_Body taz1;
     struct StyleTaz2_Body taz2;
diff --git a/tests/rust/enum.rs b/tests/rust/enum.rs
index c98e5df3..562af880 100644
--- a/tests/rust/enum.rs
+++ b/tests/rust/enum.rs
@@ -121,6 +121,12 @@ enum O {
     o4,
 }
 
+#[repr(C, u8)]
+enum P {
+    P0(u8),
+    P1(u8, u8, u8),
+}
+
 #[no_mangle]
 pub extern "C" fn root(
     opaque: *mut Opaque,
@@ -139,5 +145,6 @@ pub extern "C" fn root(
     m: M,
     n: N,
     o: O,
+    p: P,
 ) {
 }
diff --git a/tests/rust/enum.toml b/tests/rust/enum.toml
new file mode 100644
index 00000000..145e4cc9
--- /dev/null
+++ b/tests/rust/enum.toml
@@ -0,0 +1,8 @@
+trailer = """
+#include <stddef.h>
+#include "testing-helpers.h"
+static_assert(offsetof(CBINDGEN_STRUCT(P), tag) == 0, "unexpected offset for tag");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p0");
+static_assert(offsetof(CBINDGEN_STRUCT(P), p0) == 1, "unexpected offset for p1");
+static_assert(sizeof(CBINDGEN_STRUCT(P)) == 4, "unexpected size for P");
+"""
\ No newline at end of file