diff --git a/mutiny-zero/src/main/java/mutiny/zero/internal/CompletionStagePublisher.java b/mutiny-zero/src/main/java/mutiny/zero/internal/CompletionStagePublisher.java
index ede1a3d..f5f71ea 100644
--- a/mutiny-zero/src/main/java/mutiny/zero/internal/CompletionStagePublisher.java
+++ b/mutiny-zero/src/main/java/mutiny/zero/internal/CompletionStagePublisher.java
@@ -86,8 +86,9 @@ public void request(long n) {
 
         @Override
         public void cancel() {
-            cancelled.set(true);
-            completableFuture.toCompletableFuture().cancel(false);
+            if (cancelled.compareAndSet(false, true)) {
+                completableFuture.toCompletableFuture().cancel(false);
+            }
         }
     }
 }