diff --git a/src/Config/Builder.php b/src/Config/Builder.php
index 3a2bdd8..b1a8e40 100644
--- a/src/Config/Builder.php
+++ b/src/Config/Builder.php
@@ -17,7 +17,7 @@ public function build(InputInterface $input): Config
     {
         $valuesFromFile = $this->getValuesFromConfigFile($input);
         $commandLineValues = $this->valuesFromCommandLineArgs($input);
-        $configValues = array_replace_recursive($valuesFromFile, $commandLineValues);
+        $configValues = $this->mergeConfigValues($valuesFromFile, $commandLineValues);
 
         return new Config(
             $configValues['script'],
@@ -93,4 +93,18 @@ private function getValuesFromConfigFile(InputInterface $input): array
         }
         return $valuesFromFile;
     }
+
+    private function mergeConfigValues(array $valuesFromFile, array $commandLineValues): array
+    {
+        $configValues = [];
+        foreach ($commandLineValues as $key => $value) {
+            if (empty($value) && isset($valuesFromFile[$key])) {
+                $configValues[$key] = $valuesFromFile[$key];
+            } else {
+                $configValues[$key] = $commandLineValues[$key];
+            }
+        }
+
+        return $configValues;
+    }
 }
diff --git a/tests/ConfigTest.php b/tests/ConfigTest.php
index 0e82703..d81d52f 100644
--- a/tests/ConfigTest.php
+++ b/tests/ConfigTest.php
@@ -31,6 +31,32 @@ public function it_can_use_config_path_from_command_line_arg(): void
         $this->wait();
 
         $output = $watcher->getOutput();
-        $this->assertStringContainsString('directory-to-watch', $output);
+        $this->assertStringContainsString('watching: directory-to-watch', $output);
+    }
+
+    /** @test */
+    public function it_uses_values_from_config(): void
+    {
+        $configFile = Filesystem::createConfigFile(['watch' => ['first', 'second']]);
+        $fileToWatch = Filesystem::createHelloWorldPHPFile();
+
+        $watcher = (new WatcherRunner())->run($fileToWatch, ['--config', $configFile]);
+        $this->wait();
+
+        $output = $watcher->getOutput();
+        $this->assertStringContainsString('watching: first, second', $output);
+    }
+
+    /** @test */
+    public function command_line_options_override_values_from_config(): void
+    {
+        $configFile = Filesystem::createConfigFile(['watch' => ['directory-to-watch']]);
+        $fileToWatch = Filesystem::createHelloWorldPHPFile();
+
+        $watcher = (new WatcherRunner())->run($fileToWatch, ['--watch', $configFile]);
+        $this->wait();
+
+        $output = $watcher->getOutput();
+        $this->assertStringContainsString("watching: $configFile", $output);
     }
 }