diff --git a/src/build/scanner/Scanner.go b/src/build/scanner/Scanner.go
index 9725e3b..ff6ea26 100644
--- a/src/build/scanner/Scanner.go
+++ b/src/build/scanner/Scanner.go
@@ -11,4 +11,5 @@ type Scanner struct {
 	functions chan *core.Function
 	errors    chan error
 	group     sync.WaitGroup
+	queued    sync.Map
 }
diff --git a/src/build/scanner/queueDirectory.go b/src/build/scanner/queueDirectory.go
index 21b32e8..d21c8ce 100644
--- a/src/build/scanner/queueDirectory.go
+++ b/src/build/scanner/queueDirectory.go
@@ -9,6 +9,12 @@ import (
 
 // queueDirectory queues an entire directory to be scanned.
 func (s *Scanner) queueDirectory(directory string, pkg string) {
+	_, loaded := s.queued.LoadOrStore(directory, nil)
+
+	if loaded {
+		return
+	}
+
 	err := fs.Walk(directory, func(name string) {
 		if !strings.HasSuffix(name, ".q") {
 			return