diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
index 1cdf8f7..6a3d9a1 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
@@ -790,8 +790,10 @@ private Map<String, Ref> getAdvertisedOrDefaultRefs() throws IOException {
 			return refs;
 		}
 
-		advertiseRefsHook.advertiseRefs(this);
-		advertiseRefsHookCalled = true;
+		if (!advertiseRefsHookCalled) {
+			advertiseRefsHook.advertiseRefs(this);
+			advertiseRefsHookCalled = true;
+		}
 		if (refs == null) {
 			// Fall back to all refs.
 			setAdvertisedRefs(