diff --git a/src/Functions/console.php b/src/Functions/console.php
index 3b93aa2..8dd959b 100644
--- a/src/Functions/console.php
+++ b/src/Functions/console.php
@@ -79,7 +79,9 @@ function readLine(string $prompt, $stream = null): IO
  */
 function printError(string $message): IO
 {
-    return new IO(fn () => print("\033[31mError: {$message}\033[0m" . PHP_EOL));
+    return new IO(function () use ($message): void {
+        print("\033[31mError: {$message}\033[0m" . PHP_EOL);
+    });
 }
 
 const printWarning = '\Phunkie\Effect\Functions\console\printWarning';
@@ -92,7 +94,9 @@ function printError(string $message): IO
  */
 function printWarning(string $message): IO
 {
-    return new IO(fn () => print("\033[33mWarning: {$message}\033[0m" . PHP_EOL));
+    return new IO(function () use ($message): void {
+        print("\033[33mWarning: {$message}\033[0m" . PHP_EOL);
+    });
 }
 
 const printSuccess = '\Phunkie\Effect\Functions\console\printSuccess';
@@ -105,7 +109,9 @@ function printWarning(string $message): IO
  */
 function printSuccess(string $message): IO
 {
-    return new IO(fn () => print("\033[32mSuccess: {$message}\033[0m" . PHP_EOL));
+    return new IO(function () use ($message): void {
+        print("\033[32mSuccess: {$message}\033[0m" . PHP_EOL);
+    });
 }
 
 const printInfo = '\Phunkie\Effect\Functions\console\printInfo';
@@ -118,7 +124,9 @@ function printSuccess(string $message): IO
  */
 function printInfo(string $message): IO
 {
-    return new IO(fn () => print("\033[36mInfo: {$message}\033[0m" . PHP_EOL));
+    return new IO(function () use ($message): void {
+        print("\033[36mInfo: {$message}\033[0m" . PHP_EOL);
+    });
 }
 
 const printDebug = '\Phunkie\Effect\Functions\console\printDebug';
@@ -131,7 +139,9 @@ function printInfo(string $message): IO
  */
 function printDebug(string $message): IO
 {
-    return new IO(fn () => print("\033[35mDebug: {$message}\033[0m" . PHP_EOL));
+    return new IO(function () use ($message): void {
+        print("\033[35mDebug: {$message}\033[0m" . PHP_EOL);
+    });
 }
 
 const printTable = '\Phunkie\Effect\Functions\console\printTable';
diff --git a/src/IO/IOApp/OptionDefinition.php b/src/IO/IOApp/OptionDefinition.php
index fd70220..3071701 100644
--- a/src/IO/IOApp/OptionDefinition.php
+++ b/src/IO/IOApp/OptionDefinition.php
@@ -56,8 +56,12 @@ public function __construct(string $p1, string|null $p2 = null, string|OptionFor
             }
         }
 
-        if ($short === null && $long === null) {
-            throw new \InvalidArgumentException("At least one of short or long name must be provided");
+        // Emptiness rather than absence: the name is a required string and every
+        // branch above assigns it to one of the two, so neither can be null and
+        // a test for that never fired. What it meant to catch is an option no
+        // one could ever pass.
+        if (($short ?? '') === '' && ($long ?? '') === '') {
+            throw new \InvalidArgumentException('At least one of short or long name must be provided.');
         }
 
         $this->short = $short;
diff --git a/tests/Unit/IO/IOApp/OptionsTest.php b/tests/Unit/IO/IOApp/OptionsTest.php
index e027242..384c5fa 100644
--- a/tests/Unit/IO/IOApp/OptionsTest.php
+++ b/tests/Unit/IO/IOApp/OptionsTest.php
@@ -30,6 +30,19 @@ public function test_it_creates_options_with_mixed_definitions()
         $this->assertInstanceOf(Options::class, $validation->toOption()->get());
     }
 
+    // An option has to be callable by something. The guard for that could never
+    // fire, because the name is a required string and every branch assigns it,
+    // so an option with no usable name was handed back as if it were fine.
+    public function test_it_refuses_an_option_with_no_name()
+    {
+        $this->assertTrue(option('')->isLeft());
+    }
+
+    public function test_it_accepts_an_option_named_only_by_its_long_form()
+    {
+        $this->assertTrue(option('', 'verbose', 'Verbose', NoInput)->isRight());
+    }
+
     public function test_it_parses_short_flags()
     {
         $options = arguments(