diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 138b829..6bc5577 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -22,14 +22,35 @@ jobs:
       uses: actions/checkout@v2
     - name: Test
       run: |
-        go version
+        go env
         go test ./...
     - name: Test with -race
       # macos and windows tend to be a bit slower,
       # and it's rare that a race in garble would be OS-specific.
+      # also note that this can take 5-10m, so use a larger timeout.
       if: matrix.os == 'ubuntu-latest'
       run: |
-        go test -race ./...
+        go test -race -timeout=20m ./...
+
+  # We don't care about GOARCH=386 particularly,
+  # but it helps ensure we support 32-bit hosts and targets well.
+  # TODO: use CGO_ENABLED=1 once we figure out how to install gcc-multilib,
+  # and once gotooltest forwards the value of CGO_ENABLED to the scripts.
+  test-386:
+    runs-on: ubuntu-latest
+    env:
+      GOARCH: 386
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: 1.17.x
+    - name: Checkout code
+      uses: actions/checkout@v2
+    - name: Test
+      run: |
+        go env
+        go test ./...
 
   test-gotip:
     runs-on: ubuntu-latest
@@ -55,7 +76,7 @@ jobs:
       uses: actions/checkout@v2
     - name: Test
       run: |
-        go version
+        go env
         go test ./...
 
   code-checks:
diff --git a/internal/literals/swap.go b/internal/literals/swap.go
index d18e448..5fd88c1 100644
--- a/internal/literals/swap.go
+++ b/internal/literals/swap.go
@@ -17,7 +17,7 @@ type swap struct{}
 // check that the obfuscator interface is implemented
 var _ obfuscator = swap{}
 
-func getIndexType(dataLen int) string {
+func getIndexType(dataLen int64) string {
 	switch {
 	case dataLen <= math.MaxUint8:
 		return "byte"
@@ -34,7 +34,7 @@ func positionsToSlice(data []int) *ast.CompositeLit {
 	arr := &ast.CompositeLit{
 		Type: &ast.ArrayType{
 			Len: &ast.Ellipsis{}, // Performance optimization
-			Elt: ast.NewIdent(getIndexType(len(data))),
+			Elt: ast.NewIdent(getIndexType(int64(len(data)))),
 		},
 		Elts: []ast.Expr{},
 	}
diff --git a/main_test.go b/main_test.go
index 237d295..7f60fd8 100644
--- a/main_test.go
+++ b/main_test.go
@@ -87,6 +87,24 @@ func TestScripts(t *testing.T) {
 			}
 			return nil
 		},
+		// TODO: this condition should probably be supported by gotooltest
+		Condition: func(cond string) (bool, error) {
+			switch cond {
+			case "cgo":
+				out, err := exec.Command("go", "env", "CGO_ENABLED").CombinedOutput()
+				if err != nil {
+					return false, err
+				}
+				result := strings.TrimSpace(string(out))
+				switch result {
+				case "0", "1":
+					return result == "1", nil
+				default:
+					return false, fmt.Errorf("unknown CGO_ENABLED: %q", result)
+				}
+			}
+			return false, fmt.Errorf("unknown condition")
+		},
 		Cmds: map[string]func(ts *testscript.TestScript, neg bool, args []string){
 			"binsubstr":         binsubstr,
 			"bincmp":            bincmp,
diff --git a/testdata/scripts/asm.txt b/testdata/scripts/asm.txt
index 33efd5a..2e45dff 100644
--- a/testdata/scripts/asm.txt
+++ b/testdata/scripts/asm.txt
@@ -1,3 +1,6 @@
+# TODO: support arm64, at least
+[!386] [!amd64] skip 'the assembly is only written for 386 and amd64'
+
 env GOGARBLE=test/main
 
 garble build
@@ -28,29 +31,33 @@ import (
 	"test/main/imported"
 )
 
-func privateAdd(x, y int64) int64
+func privateAdd(x, y int32) int32
 
 func main() {
 	println(privateAdd(1, 2))
 	println(imported.PublicAdd(3, 4))
 }
--- main.s --
-TEXT ·privateAdd(SB),$0-24
-	MOVQ x+0(FP), BX
-	MOVQ y+8(FP), BP
-	ADDQ BP, BX
-	MOVQ BX, ret+16(FP)
+-- main_x86.s --
+//go:build 386 || amd64
+
+TEXT ·privateAdd(SB),$0-16
+	MOVL x+0(FP), BX
+	MOVL y+4(FP), BP
+	ADDL BP, BX
+	MOVL BX, ret+8(FP)
 	RET
 -- imported/imported.go --
 package imported
 
-func PublicAdd(x, y int64) int64
--- imported/imported.s --
-TEXT ·PublicAdd(SB),$0-24
-	MOVQ x+0(FP), BX
-	MOVQ y+8(FP), BP
-	ADDQ BP, BX
-	MOVQ BX, ret+16(FP)
+func PublicAdd(x, y int32) int32
+-- imported/imported_x86.s --
+//go:build 386 || amd64
+
+TEXT ·PublicAdd(SB),$0-16
+	MOVL x+0(FP), BX
+	MOVL y+4(FP), BP
+	ADDL BP, BX
+	MOVL BX, ret+8(FP)
 	RET
 -- main.stderr --
 3
diff --git a/testdata/scripts/cgo.txt b/testdata/scripts/cgo.txt
index e14c969..9144e91 100644
--- a/testdata/scripts/cgo.txt
+++ b/testdata/scripts/cgo.txt
@@ -1,3 +1,5 @@
+[!cgo] skip 'this test requires cgo to be enabled'
+
 env GOGARBLE=test/main
 
 garble build