diff --git a/src/Box.php b/src/Box.php
index 2771c21a7..15d240659 100644
--- a/src/Box.php
+++ b/src/Box.php
@@ -15,6 +15,7 @@
 namespace KevinGH\Box;
 
 use Assert\Assertion;
+use function file_exists;
 use KevinGH\Box\Compactor\PhpScoper;
 use KevinGH\Box\Composer\ComposerOrchestrator;
 use KevinGH\Box\PhpScoper\NullScoper;
@@ -240,7 +241,10 @@ public function addFile(string $file, string $contents = null, bool $binary = fa
         }
 
         if ($binary) {
-            $this->phar->addFile($file, $local);
+            true === file_exists($file)
+                ? $this->phar->addFile($file, $local)
+                : $this->phar->addFromString($local, $contents)
+            ;
         } else {
             $processedContents = self::compactContents(
                 $this->compactors,
diff --git a/tests/BoxTest.php b/tests/BoxTest.php
index 31fd5de0c..a6da0f305 100644
--- a/tests/BoxTest.php
+++ b/tests/BoxTest.php
@@ -126,6 +126,23 @@ public function test_it_can_add_a_non_exitent_file_with_contents_to_the_phar():
         $this->assertSame($expectedContents, $actualContents);
     }
 
+    public function test_it_can_add_a_non_existent_bin_file_with_contents_to_the_phar(): void
+    {
+        $file = 'foo';
+        $contents = 'test';
+
+        $this->box->addFile($file, $contents, true);
+
+        $expectedContents = $contents;
+        $expectedPharPath = 'phar://test.phar/'.$file;
+
+        $this->assertFileExists($expectedPharPath);
+
+        $actualContents = file_get_contents($expectedPharPath);
+
+        $this->assertSame($expectedContents, $actualContents);
+    }
+
     public function test_it_can_add_a_file_with_absolute_path_to_the_phar(): void
     {
         $relativePath = 'path-to/foo';