diff --git a/README.md b/README.md
index 372e1d8..2a18565 100644
--- a/README.md
+++ b/README.md
@@ -206,7 +206,7 @@ syntax.
 Pushup treats projects as their own self-contained Go module. The build
 process assumes this is the case by default. But it is possible to include a
 Pushup project as part of a parent Go module. See the the `-module` option to
-`pushup new`, and the `-build-pkg` option to the `pushup run` command.
+`pushup new`.
 
 ## Project directory structure
 
diff --git a/example/README.md b/example/README.md
index f7382e1..20cfd12 100644
--- a/example/README.md
+++ b/example/README.md
@@ -6,8 +6,5 @@ Pushup features and models how to write Pushup syntax.
 To run it, install the main Pushup app, cd to this directory, and type:
 
 ```
-pushup run -build-pkg github.com/adhocteam/pushup/example/build
+pushup run
 ```
-
-(Note that the need to type `-build-pkg ...` is temporary and will go
-away soon.)
diff --git a/go.mod b/go.mod
index 54982a5..27b6e8e 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,7 @@ go 1.18
 require (
 	github.com/fsnotify/fsnotify v1.5.4
 	github.com/google/go-cmp v0.5.8
+	golang.org/x/mod v0.7.0
 	golang.org/x/net v0.0.0-20220706163947-c90051bbdb60
 	golang.org/x/sync v0.0.0-20220601150217-0de741cfad7f
 )
diff --git a/go.sum b/go.sum
index 4c381d8..bd6188f 100644
--- a/go.sum
+++ b/go.sum
@@ -2,6 +2,8 @@ github.com/fsnotify/fsnotify v1.5.4 h1:jRbGcIw6P2Meqdwuo0H1p6JVLbL5DHKAKlYndzMwV
 github.com/fsnotify/fsnotify v1.5.4/go.mod h1:OVB6XrOHzAwXMpEM7uPOzcehqUV2UqJxmVXmkdnm1bU=
 github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
 github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+golang.org/x/mod v0.7.0 h1:LapD9S96VoQRhi/GrNTqeBJFrUjs5UHCAtTlgwA5oZA=
+golang.org/x/mod v0.7.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/net v0.0.0-20220706163947-c90051bbdb60 h1:8NSylCMxLW4JvserAndSgFL7aPli6A68yf0bYFTcWCM=
 golang.org/x/net v0.0.0-20220706163947-c90051bbdb60/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
 golang.org/x/sync v0.0.0-20220601150217-0de741cfad7f h1:Ax0t5p6N38Ga0dThY21weqDEyz2oklo4IvDkpigvkD8=
diff --git a/main.go b/main.go
index 1eac358..a3eb626 100644
--- a/main.go
+++ b/main.go
@@ -37,6 +37,7 @@ import (
 	"unicode/utf8"
 
 	"github.com/fsnotify/fsnotify"
+	"golang.org/x/mod/modfile"
 	"golang.org/x/net/html"
 	"golang.org/x/net/html/atom"
 	"golang.org/x/sync/errgroup"
@@ -240,7 +241,6 @@ func initVcs(projectDir string, vcs vcs) error {
 type buildCmd struct {
 	projectName        *regexString
 	projectDir         string
-	buildPkg           string
 	applyOptimizations bool
 	parseOnly          bool
 	codeGenOnly        bool
@@ -258,7 +258,6 @@ type buildCmd struct {
 func setBuildFlags(flags *flag.FlagSet, b *buildCmd) {
 	b.projectName = newRegexString(`^\w+`, "myproject")
 	flags.Var(b.projectName, "project", "name of Pushup project")
-	flags.StringVar(&b.buildPkg, "build-pkg", "example/myproject/build", "name of package of compiled Pushup app")
 	flags.BoolVar(&b.applyOptimizations, "O", false, "apply simple optimizations to the parse tree")
 	flags.BoolVar(&b.parseOnly, "parse-only", false, "exit after dumping parse result")
 	flags.BoolVar(&b.codeGenOnly, "codegen-only", false, "codegen only, don't compile")
@@ -339,7 +338,6 @@ func (b *buildCmd) do() error {
 	{
 		params := buildParams{
 			projectName:       b.projectName.String(),
-			pkgName:           b.buildPkg,
 			compiledOutputDir: b.outDir,
 			buildDir:          b.outDir,
 			outFile:           b.outFile,
@@ -455,7 +453,6 @@ func (r *runCmd) do() error {
 			{
 				params := buildParams{
 					projectName:       r.projectName.String(),
-					pkgName:           r.buildPkg,
 					compiledOutputDir: r.outDir,
 					buildDir:          r.outDir,
 				}
@@ -2160,7 +2157,6 @@ func copyFileFS(fsys fs.FS, dest string, src string) error {
 
 type buildParams struct {
 	projectName string
-	pkgName     string
 	// path to directory with the compiled Pushup project code
 	compiledOutputDir string
 	buildDir          string
@@ -2171,6 +2167,19 @@ type buildParams struct {
 // buildProject builds the Go program made up of the user's compiled .up
 // files and .go code, as well as Pushup's library APIs.
 func buildProject(_ context.Context, b buildParams) error {
+	var pkgName string
+	{
+		goModContents, err := os.ReadFile("go.mod")
+		if err != nil {
+			return fmt.Errorf("could not read go.mod: %w", err)
+		}
+		f, err := modfile.Parse("go.mod", goModContents, nil)
+		if err != nil {
+			return fmt.Errorf("parsing go.mod file: %w", err)
+		}
+		pkgName = f.Module.Mod.Path + "/build"
+	}
+
 	mainExeDir := filepath.Join(b.compiledOutputDir, "cmd", b.projectName)
 	if err := os.MkdirAll(mainExeDir, 0755); err != nil {
 		return fmt.Errorf("making directory for command: %w", err)
@@ -2181,7 +2190,7 @@ func buildProject(_ context.Context, b buildParams) error {
 	if err != nil {
 		return fmt.Errorf("creating main.go: %w", err)
 	}
-	if err := t.Execute(f, map[string]any{"ProjectPkg": b.pkgName}); err != nil {
+	if err := t.Execute(f, map[string]any{"ProjectPkg": pkgName}); err != nil {
 		return fmt.Errorf("executing main.go template: %w", err)
 	}
 	f.Close()
@@ -2191,7 +2200,7 @@ func buildProject(_ context.Context, b buildParams) error {
 		b.outFile = filepath.Join(b.buildDir, "bin", b.projectName)
 	}
 
-	args := []string{"build", "-o", b.outFile, filepath.Join(b.pkgName, "cmd", b.projectName)}
+	args := []string{"build", "-o", b.outFile, filepath.Join(pkgName, "cmd", b.projectName)}
 	if b.verbose {
 		fmt.Printf("build command: go %s\n", strings.Join(args, " "))
 	}
diff --git a/main_test.go b/main_test.go
index 3a91b24..1d9057f 100644
--- a/main_test.go
+++ b/main_test.go
@@ -164,7 +164,7 @@ func TestPushup(t *testing.T) {
 						var cmd *exec.Cmd
 
 						g.Go(func() error {
-							cmd = exec.Command(pushup, "run", "-build-pkg", "github.com/adhocteam/pushup/build", "-page", pushupFile, "-unix-socket", socketPath)
+							cmd = exec.Command(pushup, "run", "-page", pushupFile, "-unix-socket", socketPath)
 							sysProcAttr(cmd)
 
 							var err error