1 files changed, 4 insertions, 1 deletions
diff --git a/classic.go b/classic.go
index ef138e2..bb22b0b 100644
--- a/classic.go
+++ b/classic.go
@@ -23,6 +23,7 @@ func classic(startURL url.URL, maxConcurrency, maxURLs int) {
 
 	ctx, cancel := context.WithCancel(context.Background())
 	var wg sync.WaitGroup
+	sema := make(chan struct{}, maxConcurrency)
 
 loop:
 	for ; numPendingSends > 0; numPendingSends-- {
@@ -42,7 +43,9 @@ loop:
 					select {
 					case <-ctx.Done():
 						return
-					case worklist <- getBatch(u):
+					case sema <- struct{}{}:
+						defer func() { <-sema }()
+						worklist <- getBatch(u)
 					}
 				})
 			}