diff --git a/compileopts/config.go b/compileopts/config.go
index c8660f1c89..d7e4abe2ce 100644
--- a/compileopts/config.go
+++ b/compileopts/config.go
@@ -463,6 +463,15 @@ func (c *Config) WasmAbi() string {
 	return c.Target.WasmAbi
 }
 
+// Emulator returns the emulator target config
+func (c *Config) Emulator() []string {
+	var emulator []string
+	for _, s := range c.Target.Emulator {
+		emulator = append(emulator, strings.ReplaceAll(s, "{root}", goenv.Get("TINYGOROOT")))
+	}
+	return emulator
+}
+
 type TestConfig struct {
 	CompileTestBinary bool
 	// TODO: Filter the test functions to run, include verbose flag, etc
diff --git a/compileopts/target.go b/compileopts/target.go
index 9bbfcf9504..ffdf73652b 100644
--- a/compileopts/target.go
+++ b/compileopts/target.go
@@ -232,13 +232,6 @@ func LoadTarget(options *Options) (*TargetSpec, error) {
 		spec.ExtraFiles = append(spec.ExtraFiles, "src/internal/task/task_asyncify_wasm.S")
 	}
 
-	// TODO(dgryski): handle CFLAGS and LDFLAGS here too?
-	var emu []string
-	for _, s := range spec.Emulator {
-		emu = append(emu, strings.ReplaceAll(s, "{root}", goenv.Get("TINYGOROOT")))
-	}
-	spec.Emulator = emu
-
 	return spec, nil
 }
 
diff --git a/main.go b/main.go
index e76681870f..91ba96f660 100644
--- a/main.go
+++ b/main.go
@@ -251,7 +251,8 @@ func dirsToModuleRoot(maindir, modroot string) []string {
 // run the binary.
 func runPackageTest(config *compileopts.Config, stdout, stderr io.Writer, result builder.BuildResult, testVerbose, testShort bool, testRunRegexp string, testBenchRegexp string, testBenchTime string) (bool, error) {
 	var cmd *exec.Cmd
-	if len(config.Target.Emulator) == 0 {
+	emulator := config.Emulator()
+	if len(emulator) == 0 {
 		// Run directly.
 		var flags []string
 		if testVerbose {
@@ -272,8 +273,8 @@ func runPackageTest(config *compileopts.Config, stdout, stderr io.Writer, result
 		cmd = executeCommand(config.Options, result.Binary, flags...)
 	} else {
 		// Run in an emulator.
-		args := append(config.Target.Emulator[1:], result.Binary)
-		if config.Target.Emulator[0] == "wasmtime" {
+		args := append(emulator[1:], result.Binary)
+		if emulator[0] == "wasmtime" {
 			// create a new temp directory just for this run, announce it to os.TempDir() via TMPDIR
 			tmpdir, err := ioutil.TempDir("", "tinygotmp")
 			if err != nil {
@@ -282,10 +283,12 @@ func runPackageTest(config *compileopts.Config, stdout, stderr io.Writer, result
 			args = append(args, "--dir="+tmpdir, "--env=TMPDIR="+tmpdir)
 			// TODO: add option to not delete temp dir for debugging?
 			defer os.RemoveAll(tmpdir)
+
 			// allow reading from directories up to module root
 			for _, d := range dirsToModuleRoot(result.MainDir, result.ModuleRoot) {
 				args = append(args, "--dir="+d)
 			}
+
 			// mark end of wasmtime arguments and start of program ones: --
 			args = append(args, "--")
 			if testVerbose {
@@ -301,7 +304,7 @@ func runPackageTest(config *compileopts.Config, stdout, stderr io.Writer, result
 				args = append(args, "-test.bench="+testBenchRegexp)
 			}
 		}
-		cmd = executeCommand(config.Options, config.Target.Emulator[0], args...)
+		cmd = executeCommand(config.Options, emulator[0], args...)
 	}
 	cmd.Dir = result.MainDir
 	cmd.Stdout = stdout
@@ -499,12 +502,13 @@ func Debug(debugger, pkgName string, ocdOutput bool, options *compileopts.Option
 		gdbInterface, openocdInterface := config.Programmer()
 		switch gdbInterface {
 		case "msd", "command", "":
-			if len(config.Target.Emulator) != 0 {
-				if config.Target.Emulator[0] == "mgba" {
+			emulator := config.Emulator()
+			if len(emulator) != 0 {
+				if emulator[0] == "mgba" {
 					gdbInterface = "mgba"
-				} else if config.Target.Emulator[0] == "simavr" {
+				} else if emulator[0] == "simavr" {
 					gdbInterface = "simavr"
-				} else if strings.HasPrefix(config.Target.Emulator[0], "qemu-system-") {
+				} else if strings.HasPrefix(emulator[0], "qemu-system-") {
 					gdbInterface = "qemu"
 				} else {
 					// Assume QEMU as an emulator.
@@ -572,34 +576,34 @@ func Debug(debugger, pkgName string, ocdOutput bool, options *compileopts.Option
 			}
 		case "qemu":
 			port = ":1234"
-
+			emulator := config.Emulator()
 			// Run in an emulator.
-			args := append(config.Target.Emulator[1:], result.Binary, "-s", "-S")
-			daemon = executeCommand(config.Options, config.Target.Emulator[0], args...)
+			args := append(emulator[1:], result.Binary, "-s", "-S")
+			daemon = executeCommand(config.Options, emulator[0], args...)
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
 		case "qemu-user":
 			port = ":1234"
-
+			emulator := config.Emulator()
 			// Run in an emulator.
-			args := append(config.Target.Emulator[1:], "-g", "1234", result.Binary)
-			daemon = executeCommand(config.Options, config.Target.Emulator[0], args...)
+			args := append(emulator[1:], "-g", "1234", result.Binary)
+			daemon = executeCommand(config.Options, emulator[0], args...)
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
 		case "mgba":
 			port = ":2345"
-
+			emulator := config.Emulator()
 			// Run in an emulator.
-			args := append(config.Target.Emulator[1:], result.Binary, "-g")
-			daemon = executeCommand(config.Options, config.Target.Emulator[0], args...)
+			args := append(emulator[1:], result.Binary, "-g")
+			daemon = executeCommand(config.Options, emulator[0], args...)
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
 		case "simavr":
 			port = ":1234"
-
+			emulator := config.Emulator()
 			// Run in an emulator.
-			args := append(config.Target.Emulator[1:], "-g", result.Binary)
-			daemon = executeCommand(config.Options, config.Target.Emulator[0], args...)
+			args := append(emulator[1:], "-g", result.Binary)
+			daemon = executeCommand(config.Options, emulator[0], args...)
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
 		case "msd":
@@ -694,7 +698,8 @@ func Run(pkgName string, options *compileopts.Options) error {
 	}
 
 	return builder.Build(pkgName, ".elf", config, func(result builder.BuildResult) error {
-		if len(config.Target.Emulator) == 0 {
+		emulator := config.Emulator()
+		if len(emulator) == 0 {
 			// Run directly.
 			cmd := executeCommand(config.Options, result.Binary)
 			cmd.Stdout = os.Stdout
@@ -710,8 +715,8 @@ func Run(pkgName string, options *compileopts.Options) error {
 			return nil
 		} else {
 			// Run in an emulator.
-			args := append(config.Target.Emulator[1:], result.Binary)
-			cmd := executeCommand(config.Options, config.Target.Emulator[0], args...)
+			args := append(emulator[1:], result.Binary)
+			cmd := executeCommand(config.Options, emulator[0], args...)
 			cmd.Stdout = os.Stdout
 			cmd.Stderr = os.Stderr
 			err := cmd.Run()
diff --git a/main_test.go b/main_test.go
index 5abbc77110..cf3fc98941 100644
--- a/main_test.go
+++ b/main_test.go
@@ -377,13 +377,19 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
 	defer cancel()
 	var cmd *exec.Cmd
-	if len(spec.Emulator) == 0 {
+
+	// make sure any special vars in the emulator definition are rewritten
+	config := compileopts.Config{Target: spec}
+	emulator := config.Emulator()
+
+	if len(emulator) == 0 {
 		cmd = exec.CommandContext(ctx, binary)
 	} else {
-		args := append(spec.Emulator[1:], binary)
-		cmd = exec.CommandContext(ctx, spec.Emulator[0], args...)
+		args := append(emulator[1:], binary)
+		cmd = exec.CommandContext(ctx, emulator[0], args...)
 	}
-	if len(spec.Emulator) != 0 && spec.Emulator[0] == "wasmtime" {
+
+	if len(emulator) != 0 && emulator[0] == "wasmtime" {
 		// Allow reading from the current directory.
 		cmd.Args = append(cmd.Args, "--dir=.")
 		for _, v := range environmentVars {
@@ -399,7 +405,7 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 
 	// Run the test.
 	stdout := &bytes.Buffer{}
-	if len(spec.Emulator) != 0 && spec.Emulator[0] == "simavr" {
+	if len(emulator) != 0 && emulator[0] == "simavr" {
 		cmd.Stdout = os.Stderr
 		cmd.Stderr = stdout
 	} else {
@@ -421,7 +427,7 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 	actual := bytes.Replace(stdout.Bytes(), []byte{'\r', '\n'}, []byte{'\n'}, -1)
 	expected = bytes.Replace(expected, []byte{'\r', '\n'}, []byte{'\n'}, -1) // for Windows
 
-	if len(spec.Emulator) != 0 && spec.Emulator[0] == "simavr" {
+	if len(emulator) != 0 && emulator[0] == "simavr" {
 		// Strip simavr log formatting.
 		actual = bytes.Replace(actual, []byte{0x1b, '[', '3', '2', 'm'}, nil, -1)
 		actual = bytes.Replace(actual, []byte{0x1b, '[', '0', 'm'}, nil, -1)