diff --git a/app/Util/DependencyGraph.php b/app/Util/DependencyGraph.php
index f88e24d..f675467 100644
--- a/app/Util/DependencyGraph.php
+++ b/app/Util/DependencyGraph.php
@@ -105,6 +105,11 @@ class DependencyGraph
 			}
 		}
 
+		if (sizeof($state) == 0)
+		{
+			throw new \Exception('Cannot solve dependency graph -- no edge nodes. Circular dependency?');
+		}
+
 		// Then walk through the array and insert each node's dependencies before
 		// it recursively.
 		$iter = 0;