diff --git a/CHANGELOG.md b/CHANGELOG.md
index dbd87a60..1509f5c1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 - Breaking: generated `*.wasm.go` files will now have correct WIT kebab-case base name. Interfaces or worlds with `-` in their name will require removal of the previous `*.wasm.go` files.
 - Dropped support for TinyGo v0.32.0.
 
+### Fixed
+
+- [#284](https://github.com/bytecodealliance/go-modules/issues/284): do not use `bool` for `variant` or `result` GC shapes. TinyGo returns `result` and `variant` values with `bool` as 0 or 1, which breaks the memory representation of tagged unions (variants).
+
 ## [v0.5.0] — 2024-12-14
 
 ### Changed
diff --git a/Makefile b/Makefile
index 954b76ef..5b0f0bb2 100644
--- a/Makefile
+++ b/Makefile
@@ -53,3 +53,7 @@ test:
 	tinygo test -target=wasip1 $(GOTESTARGS) $(GOTESTMODULES)
 	tinygo test -target=wasip2 $(GOTESTARGS) $(GOTESTMODULES)
 	tinygo test -target=wasip2 $(GOTESTARGS) ./tests/...
+
+.PHONY: tests
+tests:
+	tinygo test -target=wasip2 $(GOTESTARGS) ./tests/...
diff --git a/cm/result_test.go b/cm/result_test.go
index 759c03ea..ee716bc6 100644
--- a/cm/result_test.go
+++ b/cm/result_test.go
@@ -1,6 +1,7 @@
 package cm
 
 import (
+	"fmt"
 	"runtime"
 	"testing"
 	"unsafe"
@@ -238,3 +239,98 @@ func TestIssue95BoolInt64(t *testing.T) {
 		t.Errorf("*res.OK(): %v, expected %v", got, want)
 	}
 }
+
+func TestIssue284(t *testing.T) {
+	// Using int8 instead of bool for shape works on Go and TinyGo.
+	// See https://github.com/bytecodealliance/go-modules/issues/284
+	type BoolS8Result Result[int8, bool, int8]
+
+	tests := []struct {
+		isErr bool
+		ok    bool
+		err   int8
+	}{
+		{false, false, 0},
+		{false, true, 0},
+		{true, false, 0},
+		{true, false, 1},
+		{true, false, 5},
+		{true, false, 126},
+		{true, false, 127},
+	}
+	for _, tt := range tests {
+		if !tt.isErr {
+			t.Run(fmt.Sprintf("OK[BoolS8Result](%t)", tt.ok), func(t *testing.T) {
+				r := OK[BoolS8Result](tt.ok)
+				ok, _, isErr := r.Result()
+				if isErr != tt.isErr {
+					t.Errorf("isErr == %t, expected %t", isErr, tt.isErr)
+				}
+				if ok != tt.ok {
+					t.Errorf("ok == %t, expected %t", ok, tt.ok)
+				}
+			})
+		} else {
+			t.Run(fmt.Sprintf("Err[BoolS8Result](%d)", tt.err), func(t *testing.T) {
+				r := Err[BoolS8Result](tt.err)
+				_, err, isErr := r.Result()
+				if isErr != tt.isErr {
+					t.Errorf("isErr == %t, expected %t", isErr, tt.isErr)
+				}
+				if err != tt.err {
+					t.Errorf("err == %d, expected %d", err, tt.err)
+				}
+			})
+		}
+	}
+}
+
+func TestIssue284NotTinyGo(t *testing.T) {
+	if runtime.Compiler == "tinygo" {
+		return
+	}
+
+	// Using bool as result shape changes how [OK] returns the result by value.
+	// This works on Go, but breaks on TinyGo / LLVM.
+	// See https://github.com/bytecodealliance/go-modules/issues/284
+	type BoolS8Result Result[bool, bool, int8]
+
+	tests := []struct {
+		isErr bool
+		ok    bool
+		err   int8
+	}{
+		{false, false, 0},
+		{false, true, 0},
+		{true, false, 0},
+		{true, false, 1},
+		{true, false, 5},
+		{true, false, 126},
+		{true, false, 127},
+	}
+	for _, tt := range tests {
+		if !tt.isErr {
+			t.Run(fmt.Sprintf("OK[BoolS8Result](%t)", tt.ok), func(t *testing.T) {
+				r := OK[BoolS8Result](tt.ok)
+				ok, _, isErr := r.Result()
+				if isErr != tt.isErr {
+					t.Errorf("isErr == %t, expected %t", isErr, tt.isErr)
+				}
+				if ok != tt.ok {
+					t.Errorf("ok == %t, expected %t", ok, tt.ok)
+				}
+			})
+		} else {
+			t.Run(fmt.Sprintf("Err[BoolS8Result](%d)", tt.err), func(t *testing.T) {
+				r := Err[BoolS8Result](tt.err)
+				_, err, isErr := r.Result()
+				if isErr != tt.isErr {
+					t.Errorf("isErr == %t, expected %t", isErr, tt.isErr)
+				}
+				if err != tt.err {
+					t.Errorf("err == %d, expected %d", err, tt.err)
+				}
+			})
+		}
+	}
+}
diff --git a/tests/generated/issues/issue284/i/i.wit.go b/tests/generated/issues/issue284/i/i.wit.go
new file mode 100755
index 00000000..38ba1eb2
--- /dev/null
+++ b/tests/generated/issues/issue284/i/i.wit.go
@@ -0,0 +1,13 @@
+// Code generated by wit-bindgen-go. DO NOT EDIT.
+
+// Package i represents the imported interface "issues:issue284/i".
+package i
+
+import (
+	"go.bytecodealliance.org/cm"
+)
+
+// BoolS8Result represents the result "issues:issue284/i#bool-s8-result".
+//
+//	type bool-s8-result = result<bool, s8>
+type BoolS8Result cm.Result[int8, bool, int8]
diff --git a/tests/generated/issues/issue284/w/w.wit.go b/tests/generated/issues/issue284/w/w.wit.go
new file mode 100755
index 00000000..8d8f46ab
--- /dev/null
+++ b/tests/generated/issues/issue284/w/w.wit.go
@@ -0,0 +1,4 @@
+// Code generated by wit-bindgen-go. DO NOT EDIT.
+
+// Package w represents the world "issues:issue284/w".
+package w
diff --git a/tests/generated/wasi/sockets/v0.2.0/tcp/abi.go b/tests/generated/wasi/sockets/v0.2.0/tcp/abi.go
index 2788dbeb..eb335d00 100755
--- a/tests/generated/wasi/sockets/v0.2.0/tcp/abi.go
+++ b/tests/generated/wasi/sockets/v0.2.0/tcp/abi.go
@@ -23,7 +23,7 @@ type TupleInputStreamOutputStreamShape struct {
 // IPSocketAddressShape is used for storage in variant or result types.
 type IPSocketAddressShape struct {
 	_     cm.HostLayout
-	shape [unsafe.Sizeof(network.IPSocketAddress{})]byte
+	shape [unsafe.Sizeof(IPSocketAddress{})]byte
 }
 
 func lower_IPv4Address(v network.IPv4Address) (f0 uint32, f1 uint32, f2 uint32, f3 uint32) {
diff --git a/tests/generated/wasi/sockets/v0.2.0/tcp/tcp.wasm.go b/tests/generated/wasi/sockets/v0.2.0/tcp/tcp.wasm.go
index 56247525..d6e56c26 100755
--- a/tests/generated/wasi/sockets/v0.2.0/tcp/tcp.wasm.go
+++ b/tests/generated/wasi/sockets/v0.2.0/tcp/tcp.wasm.go
@@ -46,7 +46,7 @@ func wasmimport_TCPSocketKeepAliveCount(self0 uint32, result *cm.Result[uint32,
 
 //go:wasmimport wasi:sockets/tcp@0.2.0 [method]tcp-socket.keep-alive-enabled
 //go:noescape
-func wasmimport_TCPSocketKeepAliveEnabled(self0 uint32, result *cm.Result[bool, bool, ErrorCode])
+func wasmimport_TCPSocketKeepAliveEnabled(self0 uint32, result *cm.Result[ErrorCode, bool, ErrorCode])
 
 //go:wasmimport wasi:sockets/tcp@0.2.0 [method]tcp-socket.keep-alive-idle-time
 //go:noescape
diff --git a/tests/generated/wasi/sockets/v0.2.0/tcp/tcp.wit.go b/tests/generated/wasi/sockets/v0.2.0/tcp/tcp.wit.go
index ff669440..f43fd44f 100755
--- a/tests/generated/wasi/sockets/v0.2.0/tcp/tcp.wit.go
+++ b/tests/generated/wasi/sockets/v0.2.0/tcp/tcp.wit.go
@@ -285,7 +285,7 @@ func (self TCPSocket) KeepAliveCount() (result cm.Result[uint32, uint32, ErrorCo
 //	keep-alive-enabled: func() -> result<bool, error-code>
 //
 //go:nosplit
-func (self TCPSocket) KeepAliveEnabled() (result cm.Result[bool, bool, ErrorCode]) {
+func (self TCPSocket) KeepAliveEnabled() (result cm.Result[ErrorCode, bool, ErrorCode]) {
 	self0 := cm.Reinterpret[uint32](self)
 	wasmimport_TCPSocketKeepAliveEnabled((uint32)(self0), &result)
 	return
diff --git a/tests/generated/wasi/sockets/v0.2.0/udp/abi.go b/tests/generated/wasi/sockets/v0.2.0/udp/abi.go
index 7e44e2f2..3dfaa27f 100755
--- a/tests/generated/wasi/sockets/v0.2.0/udp/abi.go
+++ b/tests/generated/wasi/sockets/v0.2.0/udp/abi.go
@@ -11,7 +11,7 @@ import (
 // IPSocketAddressShape is used for storage in variant or result types.
 type IPSocketAddressShape struct {
 	_     cm.HostLayout
-	shape [unsafe.Sizeof(network.IPSocketAddress{})]byte
+	shape [unsafe.Sizeof(IPSocketAddress{})]byte
 }
 
 func lower_IPv4Address(v network.IPv4Address) (f0 uint32, f1 uint32, f2 uint32, f3 uint32) {
diff --git a/wit/bindgen/abi.go b/wit/bindgen/abi.go
index 5b4f4d37..85fd28f4 100644
--- a/wit/bindgen/abi.go
+++ b/wit/bindgen/abi.go
@@ -6,7 +6,7 @@ import (
 	"go.bytecodealliance.org/wit"
 )
 
-// variantShape returns the type with the greatest size.
+// variantShape returns the type with the greatest size that is not a bool.
 // If there are multiple types with the same size, it returns
 // the first type that contains a pointer.
 func variantShape(types []wit.Type) wit.Type {
@@ -19,6 +19,12 @@ func variantShape(types []wit.Type) wit.Type {
 			return -1
 		case a.Size() < b.Size():
 			return 1
+		case !isBool(a) && isBool(b):
+			// bool cannot be used as variant shape
+			// See https://github.com/bytecodealliance/go-modules/issues/284
+			return -1
+		case isBool(a) && !isBool(b):
+			return 1
 		case wit.HasPointer(a) && !wit.HasPointer(b):
 			return -1
 		case !wit.HasPointer(a) && wit.HasPointer(b):
@@ -30,6 +36,16 @@ func variantShape(types []wit.Type) wit.Type {
 	return types[0]
 }
 
+func isBool(t wit.TypeDefKind) bool {
+	switch t := t.(type) {
+	case wit.Bool:
+		return true
+	case *wit.TypeDef:
+		return isBool(t.Root().Kind)
+	}
+	return false
+}
+
 // variantAlign returns the type with the largest alignment.
 func variantAlign(types []wit.Type) wit.Type {
 	if len(types) == 0 {
diff --git a/wit/bindgen/generator.go b/wit/bindgen/generator.go
index 220dcad3..553b42f4 100644
--- a/wit/bindgen/generator.go
+++ b/wit/bindgen/generator.go
@@ -1018,7 +1018,7 @@ func (g *generator) typeShape(file *gen.File, dir wit.Direction, t wit.Type) str
 }
 
 func (g *generator) typeDefShape(file *gen.File, dir wit.Direction, t *wit.TypeDef) string {
-	switch kind := t.Kind.(type) {
+	switch kind := t.Root().Kind.(type) {
 	case wit.Type:
 		return g.typeShape(file, dir, kind)
 	case *wit.Variant: