diff --git a/src/Registry/AppRegistry.php b/src/Registry/AppRegistry.php
index a0db806..f88d0ae 100644
--- a/src/Registry/AppRegistry.php
+++ b/src/Registry/AppRegistry.php
@@ -47,6 +47,11 @@ public function has(string $appName): bool
 
     public function get(string $appName): AppInterface
     {
+        if(!$this->has($appName)) {
+            throw new \InvalidArgumentException(
+                sprintf('App "%s" does not exist', $appName)
+            );
+        }
         return $this->apps[$appName];
     }
 }
diff --git a/src/Registry/ProjectRegistry.php b/src/Registry/ProjectRegistry.php
index 3e1b1fa..1b4e9a3 100644
--- a/src/Registry/ProjectRegistry.php
+++ b/src/Registry/ProjectRegistry.php
@@ -51,6 +51,11 @@ public function has(string $projectName): bool
 
     public function get(string $projectName): ProjectInterface
     {
+        if(!$this->has($projectName)) {
+            throw new \InvalidArgumentException(
+                sprintf('Project "%s" does not exist', $projectName)
+            );
+        }
         return $this->projects[$projectName];
     }
 }