diff --git a/go.mod b/go.mod
index c2a1605..8590d8d 100644
--- a/go.mod
+++ b/go.mod
@@ -3,3 +3,5 @@ module github.com/leonmika/wails-release
 go 1.25.0
 
 require golang.org/x/mod v0.35.0
+
+require github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
diff --git a/go.sum b/go.sum
index 662c524..9b4967a 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,4 @@
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 h1:El6M4kTTCOh6aBiKaUGG7oYTSPP8MxqL4YI3kZKwcP4=
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510/go.mod h1:pupxD2MaaD3pAXIBCelhxNneeOaAeabZDe5s4K6zSpQ=
 golang.org/x/mod v0.35.0 h1:Ww1D637e6Pg+Zb2KrWfHQUnH2dQRLBQyAtpr/haaJeM=
 golang.org/x/mod v0.35.0/go.mod h1:+GwiRhIInF8wPm+4AoT6L0FA1QWAad3OMdTRx4tFYlU=
diff --git a/internal/wails/build.go b/internal/wails/build.go
new file mode 100644
index 0000000..3fa6d85
--- /dev/null
+++ b/internal/wails/build.go
@@ -0,0 +1,31 @@
+package wails
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/google/shlex"
+	"github.com/leonmika/wails-release/internal/runner"
+)
+
+// BuildOpts configures a Wails build.
+type BuildOpts struct {
+	Dir        string
+	ExtraFlags string
+}
+
+// Build runs `wails build` with our mandatory flags plus any extras.
+func Build(ctx context.Context, r runner.Runner, opts BuildOpts) error {
+	args := []string{"build", "-platform", "darwin/universal", "-clean", "-trimpath"}
+	if opts.ExtraFlags != "" {
+		extra, err := shlex.Split(opts.ExtraFlags)
+		if err != nil {
+			return fmt.Errorf("parse extra-build-flags: %w", err)
+		}
+		args = append(args, extra...)
+	}
+	if _, err := r.Run(ctx, runner.Spec{Name: "wails", Args: args, Dir: opts.Dir}); err != nil {
+		return fmt.Errorf("wails build: %w", err)
+	}
+	return nil
+}
diff --git a/internal/wails/build_test.go b/internal/wails/build_test.go
new file mode 100644
index 0000000..1aa2656
--- /dev/null
+++ b/internal/wails/build_test.go
@@ -0,0 +1,57 @@
+package wails_test
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/leonmika/wails-release/internal/runner"
+	"github.com/leonmika/wails-release/internal/wails"
+)
+
+func TestBuild_DefaultArgs(t *testing.T) {
+	f := &runner.Fake{}
+	f.On("wails", nil).Return(nil, nil)
+
+	err := wails.Build(context.Background(), f, wails.BuildOpts{Dir: "/work"})
+	if err != nil {
+		t.Fatalf("unexpected: %v", err)
+	}
+	want := []string{"build", "-platform", "darwin/universal", "-clean", "-trimpath"}
+	if !reflect.DeepEqual(f.Calls[0].Args, want) {
+		t.Fatalf("args got %v want %v", f.Calls[0].Args, want)
+	}
+	if f.Calls[0].Dir != "/work" {
+		t.Fatalf("dir got %q want /work", f.Calls[0].Dir)
+	}
+}
+
+func TestBuild_AppendsExtraFlags(t *testing.T) {
+	f := &runner.Fake{}
+	f.On("wails", nil).Return(nil, nil)
+
+	err := wails.Build(context.Background(), f, wails.BuildOpts{
+		Dir:        "/work",
+		ExtraFlags: `-tags release -ldflags "-X main.commit=abc"`,
+	})
+	if err != nil {
+		t.Fatalf("unexpected: %v", err)
+	}
+	want := []string{
+		"build", "-platform", "darwin/universal", "-clean", "-trimpath",
+		"-tags", "release", "-ldflags", "-X main.commit=abc",
+	}
+	if !reflect.DeepEqual(f.Calls[0].Args, want) {
+		t.Fatalf("args got %v want %v", f.Calls[0].Args, want)
+	}
+}
+
+func TestBuild_MalformedExtraFlagsErrors(t *testing.T) {
+	err := wails.Build(context.Background(), &runner.Fake{}, wails.BuildOpts{
+		Dir:        "/work",
+		ExtraFlags: `-foo "unterminated`,
+	})
+	if err == nil {
+		t.Fatal("expected parse error")
+	}
+}