diff --git a/nucleus/grizzly/config/src/main/java/org/glassfish/grizzly/config/HSTSFilter.java b/nucleus/grizzly/config/src/main/java/org/glassfish/grizzly/config/HSTSFilter.java
index eb4fecf2bc2..a881126da13 100644
--- a/nucleus/grizzly/config/src/main/java/org/glassfish/grizzly/config/HSTSFilter.java
+++ b/nucleus/grizzly/config/src/main/java/org/glassfish/grizzly/config/HSTSFilter.java
@@ -88,7 +88,9 @@ public NextAction handleRead(FilterChainContext ctx) throws IOException {
         Object message = ctx.getMessage();
         if (message instanceof HttpContent && enabled) {
             HttpContent content = (HttpContent) message;
-            content.getHttpHeader().addHeader(HSTS_HEADER, header);
+            if(!content.getHttpHeader().containsHeader(HSTS_HEADER)) {
+                content.getHttpHeader().addHeader(HSTS_HEADER, header);
+            }
         }     
         
         return ctx.getInvokeAction();