diff --git a/compileopts/config.go b/compileopts/config.go
index 9fb6a3bb..d7dbb41c 100644
--- a/compileopts/config.go
+++ b/compileopts/config.go
@@ -10,6 +10,7 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/google/shlex"
 	"github.com/tinygo-org/tinygo/goenv"
 )
 
@@ -494,13 +495,38 @@ func (c *Config) WasmAbi() string {
 	return c.Target.WasmAbi
 }
 
-// Emulator returns the emulator target config
-func (c *Config) Emulator() []string {
+// EmulatorName is a shorthand to get the command for this emulator, something
+// like qemu-system-arm or simavr.
+func (c *Config) EmulatorName() string {
+	parts := strings.SplitN(c.Target.Emulator, " ", 2)
+	if len(parts) > 1 {
+		return parts[0]
+	}
+	return ""
+}
+
+// EmulatorFormat returns the binary format for the emulator and the associated
+// file extension. An empty string means to pass directly whatever the linker
+// produces directly without conversion.
+func (c *Config) EmulatorFormat() (format, fileExt string) {
+	return "", ""
+}
+
+// Emulator returns a ready-to-run command to run the given binary in an
+// emulator. Give it the format (returned by EmulatorFormat()) and the path to
+// the compiled binary.
+func (c *Config) Emulator(format, binary string) ([]string, error) {
+	parts, err := shlex.Split(c.Target.Emulator)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse emulator command: %w", err)
+	}
 	var emulator []string
-	for _, s := range c.Target.Emulator {
-		emulator = append(emulator, strings.ReplaceAll(s, "{root}", goenv.Get("TINYGOROOT")))
+	for _, s := range parts {
+		s = strings.ReplaceAll(s, "{root}", goenv.Get("TINYGOROOT"))
+		s = strings.ReplaceAll(s, "{"+format+"}", binary)
+		emulator = append(emulator, s)
 	}
-	return emulator
+	return emulator, nil
 }
 
 type TestConfig struct {
diff --git a/compileopts/target.go b/compileopts/target.go
index 26f00753..6a1dbf12 100644
--- a/compileopts/target.go
+++ b/compileopts/target.go
@@ -44,8 +44,8 @@ type TargetSpec struct {
 	LDFlags          []string `json:"ldflags"`
 	LinkerScript     string   `json:"linkerscript"`
 	ExtraFiles       []string `json:"extra-files"`
-	RP2040BootPatch  *bool    `json:"rp2040-boot-patch"`        // Patch RP2040 2nd stage bootloader checksum
-	Emulator         []string `json:"emulator" override:"copy"` // inherited Emulator must not be append
+	RP2040BootPatch  *bool    `json:"rp2040-boot-patch"` // Patch RP2040 2nd stage bootloader checksum
+	Emulator         string   `json:"emulator"`
 	FlashCommand     string   `json:"flash-command"`
 	GDB              []string `json:"gdb"`
 	PortReset        string   `json:"flash-1200-bps-reset"`
@@ -90,19 +90,8 @@ func (spec *TargetSpec) overrideProperties(child *TargetSpec) {
 			if !src.IsNil() {
 				dst.Set(src)
 			}
-		case reflect.Slice: // for slices...
-			if src.Len() > 0 { // ... if not empty ...
-				switch tag := field.Tag.Get("override"); tag {
-				case "copy":
-					// copy the field of child to spec
-					dst.Set(src)
-				case "append", "":
-					// or append the field of child to spec
-					dst.Set(reflect.AppendSlice(dst, src))
-				default:
-					panic("override mode must be 'copy' or 'append' (default). I don't know how to '" + tag + "'.")
-				}
-			}
+		case reflect.Slice: // for slices, append the field
+			dst.Set(reflect.AppendSlice(dst, src))
 		default:
 			panic("unknown field type : " + kind.String())
 		}
@@ -335,20 +324,20 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 			case "386":
 				// amd64 can _usually_ run 32-bit programs, so skip the emulator in that case.
 				if runtime.GOARCH != "amd64" {
-					spec.Emulator = []string{"qemu-i386"}
+					spec.Emulator = "qemu-i386 {}"
 				}
 			case "amd64":
-				spec.Emulator = []string{"qemu-x86_64"}
+				spec.Emulator = "qemu-x86_64 {}"
 			case "arm":
-				spec.Emulator = []string{"qemu-arm"}
+				spec.Emulator = "qemu-arm {}"
 			case "arm64":
-				spec.Emulator = []string{"qemu-aarch64"}
+				spec.Emulator = "qemu-aarch64 {}"
 			}
 		}
 	}
 	if goos != runtime.GOOS {
 		if goos == "windows" {
-			spec.Emulator = []string{"wine"}
+			spec.Emulator = "wine {}"
 		}
 	}
 	return &spec, nil
diff --git a/compileopts/target_test.go b/compileopts/target_test.go
index 6aea7e81..8f7b99b2 100644
--- a/compileopts/target_test.go
+++ b/compileopts/target_test.go
@@ -29,7 +29,6 @@ func TestOverrideProperties(t *testing.T) {
 		CPU:              "baseCpu",
 		CFlags:           []string{"-base-foo", "-base-bar"},
 		BuildTags:        []string{"bt1", "bt2"},
-		Emulator:         []string{"be1", "be2"},
 		DefaultStackSize: 42,
 		AutoStackSize:    &baseAutoStackSize,
 	}
@@ -38,7 +37,6 @@ func TestOverrideProperties(t *testing.T) {
 		GOOS:             "",
 		CPU:              "chlidCpu",
 		CFlags:           []string{"-child-foo", "-child-bar"},
-		Emulator:         []string{"ce1", "ce2"},
 		AutoStackSize:    &childAutoStackSize,
 		DefaultStackSize: 64,
 	}
@@ -57,9 +55,6 @@ func TestOverrideProperties(t *testing.T) {
 	if !reflect.DeepEqual(base.BuildTags, []string{"bt1", "bt2"}) {
 		t.Errorf("Overriding failed : got %v", base.BuildTags)
 	}
-	if !reflect.DeepEqual(base.Emulator, []string{"ce1", "ce2"}) {
-		t.Errorf("Overriding failed : got %v", base.Emulator)
-	}
 	if *base.AutoStackSize != false {
 		t.Errorf("Overriding failed : got %v", base.AutoStackSize)
 	}
diff --git a/main.go b/main.go
index b9b7626b..0cb8a42c 100644
--- a/main.go
+++ b/main.go
@@ -239,8 +239,7 @@ func Test(pkgName string, stdout, stderr io.Writer, options *compileopts.Options
 		cmd.Dir = result.MainDir
 
 		// Wasmtime needs a few extra flags to work.
-		emulator := config.Emulator()
-		if len(emulator) != 0 && emulator[0] == "wasmtime" {
+		if config.EmulatorName() == "wasmtime" {
 			// Add directories to the module root, but skip the current working
 			// directory which is already added by buildAndRun.
 			dirs := dirsToModuleRoot(result.MainDir, result.ModuleRoot)
@@ -484,18 +483,19 @@ func Debug(debugger, pkgName string, ocdOutput bool, options *compileopts.Option
 		return err
 	}
 
-	return builder.Build(pkgName, "", config, func(result builder.BuildResult) error {
+	format, fileExt := config.EmulatorFormat()
+	return builder.Build(pkgName, fileExt, config, func(result builder.BuildResult) error {
 		// Find a good way to run GDB.
 		gdbInterface, openocdInterface := config.Programmer()
 		switch gdbInterface {
 		case "msd", "command", "":
-			emulator := config.Emulator()
-			if len(emulator) != 0 {
-				if emulator[0] == "mgba" {
+			emulator := config.EmulatorName()
+			if emulator != "" {
+				if emulator == "mgba" {
 					gdbInterface = "mgba"
-				} else if emulator[0] == "simavr" {
+				} else if emulator == "simavr" {
 					gdbInterface = "simavr"
-				} else if strings.HasPrefix(emulator[0], "qemu-system-") {
+				} else if strings.HasPrefix(emulator, "qemu-system-") {
 					gdbInterface = "qemu"
 				} else {
 					// Assume QEMU as an emulator.
@@ -514,6 +514,10 @@ func Debug(debugger, pkgName string, ocdOutput bool, options *compileopts.Option
 		port := ""
 		var gdbCommands []string
 		var daemon *exec.Cmd
+		emulator, err := config.Emulator(format, result.Binary)
+		if err != nil {
+			return err
+		}
 		switch gdbInterface {
 		case "native":
 			// Run GDB directly.
@@ -563,33 +567,29 @@ func Debug(debugger, pkgName string, ocdOutput bool, options *compileopts.Option
 			}
 		case "qemu":
 			port = ":1234"
-			emulator := config.Emulator()
 			// Run in an emulator.
-			args := append(emulator[1:], result.Binary, "-s", "-S")
+			args := append(emulator[1:], "-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(emulator[1:], "-g", "1234", result.Binary)
+			args := append(emulator[1:], "-g", "1234")
 			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(emulator[1:], result.Binary, "-g")
+			args := append(emulator[1:], "-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(emulator[1:], "-g", result.Binary)
+			args := append(emulator[1:], "-g")
 			daemon = executeCommand(config.Options, emulator[0], args...)
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
@@ -666,7 +666,7 @@ func Debug(debugger, pkgName string, ocdOutput bool, options *compileopts.Option
 		cmd.Stdin = os.Stdin
 		cmd.Stdout = os.Stdout
 		cmd.Stderr = os.Stderr
-		err := cmd.Run()
+		err = cmd.Run()
 		if err != nil {
 			return &commandError{"failed to run " + cmdName + " with", result.Binary, err}
 		}
@@ -694,9 +694,6 @@ func Run(pkgName string, options *compileopts.Options, cmdArgs []string) error {
 // passes command line arguments and evironment variables in a way appropriate
 // for the given emulator.
 func buildAndRun(pkgName string, config *compileopts.Config, stdout io.Writer, cmdArgs, environmentVars []string, timeout time.Duration, run func(cmd *exec.Cmd, result builder.BuildResult) error) error {
-	// make sure any special vars in the emulator definition are rewritten
-	emulator := config.Emulator()
-
 	// Determine whether we're on a system that supports environment variables
 	// and command line parameters (operating systems, WASI) or not (baremetal,
 	// WebAssembly in the browser). If we're on a system without an environment,
@@ -728,7 +725,7 @@ func buildAndRun(pkgName string, config *compileopts.Config, stdout io.Writer, c
 				"runtime": runtimeGlobals,
 			}
 		}
-	} else if len(emulator) != 0 && emulator[0] == "wasmtime" {
+	} else if config.EmulatorName() == "wasmtime" {
 		// Wasmtime needs some special flags to pass environment variables
 		// and allow reading from the current directory.
 		args = append(args, "--dir=.")
@@ -747,7 +744,8 @@ func buildAndRun(pkgName string, config *compileopts.Config, stdout io.Writer, c
 		env = environmentVars
 	}
 
-	return builder.Build(pkgName, "", config, func(result builder.BuildResult) error {
+	format, fileExt := config.EmulatorFormat()
+	return builder.Build(pkgName, fileExt, config, func(result builder.BuildResult) error {
 		// If needed, set a timeout on the command. This is done in tests so
 		// they don't waste resources on a stalled test.
 		var ctx context.Context
@@ -759,12 +757,15 @@ func buildAndRun(pkgName string, config *compileopts.Config, stdout io.Writer, c
 
 		// Set up the command.
 		var name string
-		if len(emulator) == 0 {
+		if config.Target.Emulator == "" {
 			name = result.Binary
 		} else {
+			emulator, err := config.Emulator(format, result.Binary)
+			if err != nil {
+				return err
+			}
 			name = emulator[0]
 			emuArgs := append([]string(nil), emulator[1:]...)
-			emuArgs = append(emuArgs, result.Binary)
 			args = append(emuArgs, args...)
 		}
 		var cmd *exec.Cmd
@@ -779,7 +780,7 @@ func buildAndRun(pkgName string, config *compileopts.Config, stdout io.Writer, c
 		// stdout.
 		cmd.Stdout = stdout
 		cmd.Stderr = os.Stderr
-		if len(emulator) != 0 && emulator[0] == "simavr" {
+		if config.EmulatorName() == "simavr" {
 			cmd.Stdout = nil // don't print initial load commands
 			cmd.Stderr = stdout
 		}
@@ -1572,7 +1573,7 @@ func main() {
 				os.Exit(1)
 				return
 			}
-			if spec.FlashMethod == "" && spec.FlashCommand == "" && spec.Emulator == nil {
+			if spec.FlashMethod == "" && spec.FlashCommand == "" && spec.Emulator == "" {
 				// This doesn't look like a regular target file, but rather like
 				// a parent target (such as targets/cortex-m.json).
 				continue
diff --git a/main_test.go b/main_test.go
index efb4b514..3b088ada 100644
--- a/main_test.go
+++ b/main_test.go
@@ -223,7 +223,7 @@ func runPlatTests(options compileopts.Options, tests []string, t *testing.T) {
 			runTest(name, options, t, nil, nil)
 		})
 	}
-	if len(spec.Emulator) == 0 || spec.Emulator[0] != "simavr" {
+	if !strings.HasPrefix(spec.Emulator, "simavr ") {
 		t.Run("env.go", func(t *testing.T) {
 			t.Parallel()
 			runTest("env.go", options, t, []string{"first", "second"}, []string{"ENV1=VALUE1", "ENV2=VALUE2"})
@@ -257,8 +257,8 @@ func emuCheck(t *testing.T, options compileopts.Options) {
 	if err != nil {
 		t.Fatal("failed to load target spec:", err)
 	}
-	if len(spec.Emulator) != 0 {
-		_, err := exec.LookPath(spec.Emulator[0])
+	if spec.Emulator != "" {
+		_, err := exec.LookPath(strings.SplitN(spec.Emulator, " ", 2)[0])
 		if err != nil {
 			if errors.Is(err, exec.ErrNotFound) {
 				t.Skipf("emulator not installed: %q", spec.Emulator[0])
@@ -327,9 +327,6 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 		t.Fatal(err)
 	}
 
-	// make sure any special vars in the emulator definition are rewritten
-	emulator := config.Emulator()
-
 	// Build the test binary.
 	stdout := &bytes.Buffer{}
 	err = buildAndRun("./"+path, config, stdout, cmdArgs, environmentVars, time.Minute, func(cmd *exec.Cmd, result builder.BuildResult) error {
@@ -345,7 +342,7 @@ 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(emulator) != 0 && emulator[0] == "simavr" {
+	if config.EmulatorName() == "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)
diff --git a/targets/arduino-nano.json b/targets/arduino-nano.json
index 9f3a3b9f..548e87b1 100644
--- a/targets/arduino-nano.json
+++ b/targets/arduino-nano.json
@@ -6,5 +6,5 @@
 		"-Wl,--defsym=_stack_size=512"
 	],
 	"flash-command": "avrdude -c arduino -p atmega328p -b 57600 -P {port} -U flash:w:{hex}:i",
-	"emulator": ["simavr", "-m", "atmega328p", "-f", "16000000"]
+	"emulator": "simavr -m atmega328p -f 16000000 {}"
 }
diff --git a/targets/arduino.json b/targets/arduino.json
index 91dc49b8..f2702304 100644
--- a/targets/arduino.json
+++ b/targets/arduino.json
@@ -7,5 +7,5 @@
 	],
 	"flash-command": "avrdude -c arduino -p atmega328p -P {port} -U flash:w:{hex}:i",
 	"serial-port": ["acm:2341:0043", "acm:2341:0001", "acm:2a03:0043", "acm:2341:0243"],
-	"emulator": ["simavr", "-m", "atmega328p", "-f", "16000000"]
+	"emulator": "simavr -m atmega328p -f 16000000 {}"
 }
diff --git a/targets/atmega1284p.json b/targets/atmega1284p.json
index 7740ccf1..d78d6a2a 100644
--- a/targets/atmega1284p.json
+++ b/targets/atmega1284p.json
@@ -13,5 +13,5 @@
         "targets/avr.S",
         "src/device/avr/atmega1284p.s"
     ],
-    "emulator": ["simavr", "-m", "atmega1284p", "-f", "20000000"]
+    "emulator": "simavr -m atmega1284p -f 20000000 {}"
 }
diff --git a/targets/cortex-m-qemu.json b/targets/cortex-m-qemu.json
index 1d1cfc89..80e087aa 100644
--- a/targets/cortex-m-qemu.json
+++ b/targets/cortex-m-qemu.json
@@ -5,5 +5,5 @@
 	"extra-files": [
 		"targets/cortex-m-qemu.s"
 	],
-	"emulator": ["qemu-system-arm", "-machine", "lm3s6965evb", "-semihosting", "-nographic", "-kernel"]
+	"emulator": "qemu-system-arm -machine lm3s6965evb -semihosting -nographic -kernel {}"
 }
diff --git a/targets/digispark.json b/targets/digispark.json
index 14606b04..ad9b1550 100644
--- a/targets/digispark.json
+++ b/targets/digispark.json
@@ -6,5 +6,5 @@
 		"-Wl,--defsym=_stack_size=128"
 	],
 	"flash-command": "micronucleus --run {hex}",
-	"emulator": ["simavr", "-m", "attiny85", "-f", "16000000"]
+	"emulator": "simavr -m attiny85 -f 16000000 {}"
 }
diff --git a/targets/gameboy-advance.json b/targets/gameboy-advance.json
index 8f46c642..0ead0831 100644
--- a/targets/gameboy-advance.json
+++ b/targets/gameboy-advance.json
@@ -24,5 +24,5 @@
 		"src/runtime/gc_arm.S"
 	],
 	"gdb": ["gdb-multiarch"],
-	"emulator": ["mgba", "-3"]
+	"emulator": "mgba -3 {}"
 }
diff --git a/targets/hifive1-qemu.json b/targets/hifive1-qemu.json
index 11518943..5d2d3143 100644
--- a/targets/hifive1-qemu.json
+++ b/targets/hifive1-qemu.json
@@ -4,5 +4,5 @@
 	"serial": "uart",
 	"default-stack-size": 4096,
 	"linkerscript": "targets/hifive1-qemu.ld",
-	"emulator": ["qemu-system-riscv32", "-machine", "sifive_e", "-nographic", "-kernel"]
+	"emulator": "qemu-system-riscv32 -machine sifive_e -nographic -kernel {}"
 }
diff --git a/targets/riscv-qemu.json b/targets/riscv-qemu.json
index ebc220e9..84050ff6 100644
--- a/targets/riscv-qemu.json
+++ b/targets/riscv-qemu.json
@@ -4,5 +4,5 @@
 	"build-tags": ["virt", "qemu"],
 	"default-stack-size": 4096,
 	"linkerscript": "targets/riscv-qemu.ld",
-	"emulator": ["qemu-system-riscv32", "-machine", "virt", "-nographic", "-bios", "none", "-kernel"]
+	"emulator": "qemu-system-riscv32 -machine virt -nographic -bios none -kernel {}"
 }
diff --git a/targets/wasi.json b/targets/wasi.json
index 9ae96a33..8ff4c3a2 100644
--- a/targets/wasi.json
+++ b/targets/wasi.json
@@ -13,6 +13,6 @@
 		"--stack-first",
 		"--no-demangle"
 	],
-	"emulator":      ["wasmtime"],
+	"emulator":      "wasmtime {}",
 	"wasm-abi":      "generic"
 }
diff --git a/targets/wasm.json b/targets/wasm.json
index 12857dc1..1cc3410d 100644
--- a/targets/wasm.json
+++ b/targets/wasm.json
@@ -13,6 +13,6 @@
 		"--stack-first",
 		"--no-demangle"
 	],
-	"emulator":      ["node", "{root}/targets/wasm_exec.js"],
+	"emulator":      "node {root}/targets/wasm_exec.js {}",
 	"wasm-abi":      "js"
 }