diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractMessageConverterMethodProcessor.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractMessageConverterMethodProcessor.java
index 32084d33e5c0..396962a2f40a 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractMessageConverterMethodProcessor.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractMessageConverterMethodProcessor.java
@@ -459,7 +459,10 @@ private void determineCompatibleMediaTypes(
 		for (MediaType requestedType : acceptableTypes) {
 			for (MediaType producibleType : producibleTypes) {
 				if (requestedType.isCompatibleWith(producibleType)) {
-					mediaTypesToUse.add(getMostSpecificMediaType(requestedType, producibleType));
+					MediaType mostSpecificMediaType = getMostSpecificMediaType(requestedType, producibleType);
+					if (!mediaTypesToUse.contains(mostSpecificMediaType)) {
+						mediaTypesToUse.add(mostSpecificMediaType);
+					}
 				}
 			}
 		}