diff --git a/src/Runner/CliTester.php b/src/Runner/CliTester.php
index b51de53e..d923d101 100644
--- a/src/Runner/CliTester.php
+++ b/src/Runner/CliTester.php
@@ -267,7 +267,7 @@ private function prepareCodeCoverage(Runner $runner): string
 	{
 		$engines = $this->interpreter->getCodeCoverageEngines();
 		if (count($engines) < 1) {
-			throw new \Exception("Code coverage functionality requires Xdebug or PCOV extension or PHPDBG SAPI (used {$this->interpreter->getCommandLine()})");
+			throw new \Exception("Code coverage functionality requires Xdebug or PCOV extension or PHPDBG SAPI (used {$this->interpreter->getCommandLineStr()})");
 		}
 
 		file_put_contents($this->options['--coverage'], '');
diff --git a/src/Runner/Job.php b/src/Runner/Job.php
index 135e5695..e7379a4d 100644
--- a/src/Runner/Job.php
+++ b/src/Runner/Job.php
@@ -95,7 +95,7 @@ public function run(bool $async = false): void
 		$this->duration = -microtime(as_float: true);
 		$this->proc = proc_open(
 			$this->interpreter
-				->withArguments(['-d register_argc_argv=on', $this->test->getFile(), ...$args])
+				->withArguments(['-d', 'register_argc_argv=on', $this->test->getFile(), ...$args])
 				->getCommandLine(),
 			[
 				['pipe', 'r'],
diff --git a/src/Runner/Output/ConsolePrinter.php b/src/Runner/Output/ConsolePrinter.php
index ca47254a..311bf7ae 100644
--- a/src/Runner/Output/ConsolePrinter.php
+++ b/src/Runner/Output/ConsolePrinter.php
@@ -67,7 +67,7 @@ public function begin(): void
 			$this->mode = self::ModeLines;
 		}
 		fwrite($this->file, $this->runner->getInterpreter()->getShortInfo()
-			. ' | ' . $this->runner->getInterpreter()->getCommandLine()
+			. ' | ' . $this->runner->getInterpreter()->getCommandLineStr()
 			. " | {$this->runner->threadCount} thread" . ($this->runner->threadCount > 1 ? 's' : '') . "\n\n");
 	}
 
diff --git a/src/Runner/Output/Logger.php b/src/Runner/Output/Logger.php
index a41fbdbc..cab95e8a 100644
--- a/src/Runner/Output/Logger.php
+++ b/src/Runner/Output/Logger.php
@@ -38,7 +38,7 @@ public function begin(): void
 		$this->count = 0;
 		$this->results = [Test::Passed => 0, Test::Skipped => 0, Test::Failed => 0];
 		fwrite($this->file, 'PHP ' . $this->runner->getInterpreter()->getVersion()
-			. ' | ' . $this->runner->getInterpreter()->getCommandLine()
+			. ' | ' . $this->runner->getInterpreter()->getCommandLineStr()
 			. " | {$this->runner->threadCount} threads\n\n");
 	}
 
diff --git a/src/Runner/PhpInterpreter.php b/src/Runner/PhpInterpreter.php
index 908b1614..b31b9b30 100644
--- a/src/Runner/PhpInterpreter.php
+++ b/src/Runner/PhpInterpreter.php
@@ -16,7 +16,7 @@
  */
 class PhpInterpreter
 {
-	private string $commandLine;
+	private array $commandLine;
 	private bool $cgi;
 	private \stdClass $info;
 	private string $error;
@@ -25,14 +25,10 @@ class PhpInterpreter
 	/** @param string[]  $args */
 	public function __construct(string $path, array $args = [])
 	{
-		$this->commandLine = Helpers::escapeArg($path);
 		$proc = @proc_open( // @ is escalated to exception
-			$this->commandLine . ' --version',
+			[$path, '--version'],
 			[['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']],
 			$pipes,
-			null,
-			null,
-			['bypass_shell' => true],
 		);
 		if ($proc === false) {
 			throw new \Exception("Cannot run PHP interpreter $path. Use -p option.");
@@ -42,20 +38,22 @@ public function __construct(string $path, array $args = [])
 		$output = stream_get_contents($pipes[1]);
 		proc_close($proc);
 
-		$args = ' ' . implode(' ', array_map([Helpers::class, 'escapeArg'], $args));
+		$this->commandLine = array_merge([$path], $args);
 		if (str_contains($output, 'phpdbg')) {
-			$args = ' -qrrb -S cli' . $args;
+			array_push($this->commandLine, '-qrrb', '-S', 'cli');
 		}
 
-		$this->commandLine .= rtrim($args);
-
 		$proc = proc_open(
-			$this->commandLine . ' -d register_argc_argv=on ' . Helpers::escapeArg(__DIR__ . '/info.php') . ' serialized',
+			array_merge(
+				$this->commandLine,
+				[
+					'-d', 'register_argc_argv=on',
+					__DIR__ . '/info.php',
+					'serialized',
+				],
+			),
 			[['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']],
 			$pipes,
-			null,
-			null,
-			['bypass_shell' => true],
 		) ?: throw new \Exception("Unable to run $path.");
 
 		$output = stream_get_contents($pipes[1]);
@@ -88,7 +86,7 @@ public function __construct(string $path, array $args = [])
 	public function withArguments(array $args): static
 	{
 		$me = clone $this;
-		$me->commandLine .= ' ' . implode(' ', array_map([Helpers::class, 'escapeArg'], $args));
+		array_push($me->commandLine, ...$args);
 		return $me;
 	}
 
@@ -98,16 +96,22 @@ public function withArguments(array $args): static
 	 */
 	public function withPhpIniOption(string $name, ?string $value = null): static
 	{
-		return $this->withArguments(['-d ' . $name . ($value === null ? '' : "=$value")]);
+		return $this->withArguments(['-d', $name . ($value === null ? '' : "=$value")]);
 	}
 
 
-	public function getCommandLine(): string
+	public function getCommandLine(): array
 	{
 		return $this->commandLine;
 	}
 
 
+	public function getCommandLineStr(): string
+	{
+		return implode(' ', array_map([Helpers::class, 'escapeArg'], $this->commandLine));
+	}
+
+
 	public function getVersion(): string
 	{
 		return $this->info->version;
diff --git a/tests/Runner/PhpInterpreter.phpt b/tests/Runner/PhpInterpreter.phpt
index 7715a776..19f9b1f9 100644
--- a/tests/Runner/PhpInterpreter.phpt
+++ b/tests/Runner/PhpInterpreter.phpt
@@ -35,6 +35,6 @@ Assert::count($count, $engines);
 
 // createInterpreter() uses same php.ini as parent
 if (!$interpreter->isCgi()) {
-	$output = shell_exec($interpreter->withArguments(['-r echo php_ini_loaded_file();'])->getCommandLine());
+	$output = shell_exec($interpreter->withArguments(['-r', 'echo php_ini_loaded_file();'])->getCommandLineStr());
 	Assert::same(php_ini_loaded_file(), $output);
 }