diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/BasicHttpCache.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/BasicHttpCache.java
index 2ab7217bd..b2240e655 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/BasicHttpCache.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/BasicHttpCache.java
@@ -30,6 +30,7 @@ import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.apache.http.annotation.ThreadSafe;
 import org.apache.http.client.cache.HttpCacheOperationException;
 import org.apache.http.client.cache.HttpCacheUpdateCallback;
 import org.apache.http.client.cache.HttpCache;
@@ -39,6 +40,7 @@ import org.apache.http.client.cache.HttpCache;
  *
  * @since 4.1
  */
+@ThreadSafe
 public class BasicHttpCache implements HttpCache<CacheEntry> {
 
     private final LinkedHashMap<String, CacheEntry> baseMap = new LinkedHashMap<String, CacheEntry>(20,
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheEntryGenerator.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheEntryGenerator.java
index f7de06eaf..00ef83540 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheEntryGenerator.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheEntryGenerator.java
@@ -30,10 +30,12 @@ import java.io.IOException;
 import java.util.Date;
 
 import org.apache.http.HttpResponse;
+import org.apache.http.annotation.Immutable;
 
 /**
  * @since 4.1
  */
+@Immutable
 public class CacheEntryGenerator {
 
     public CacheEntry generateEntry(Date requestDate, Date responseDate, HttpResponse response,
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheEntryUpdater.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheEntryUpdater.java
index b592a49ef..8575e375e 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheEntryUpdater.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheEntryUpdater.java
@@ -34,12 +34,14 @@ import java.util.ListIterator;
 
 import org.apache.http.Header;
 import org.apache.http.HttpResponse;
+import org.apache.http.annotation.Immutable;
 import org.apache.http.impl.cookie.DateParseException;
 import org.apache.http.impl.cookie.DateUtils;
 
 /**
  * @since 4.1
  */
+@Immutable
 public class CacheEntryUpdater {
 
     public void updateCacheEntry(CacheEntry entry, Date requestDate, Date responseDate,
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheInvalidator.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheInvalidator.java
index 28b7b2459..60a4dc968 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheInvalidator.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheInvalidator.java
@@ -32,6 +32,7 @@ import org.apache.http.Header;
 import org.apache.http.HeaderElement;
 import org.apache.http.HttpHost;
 import org.apache.http.HttpRequest;
+import org.apache.http.annotation.Immutable;
 import org.apache.http.client.cache.HttpCacheOperationException;
 import org.apache.http.client.cache.HttpCache;
 
@@ -41,6 +42,7 @@ import org.apache.http.client.cache.HttpCache;
  *
  * @since 4.1
  */
+@Immutable
 public class CacheInvalidator {
 
     private final HttpCache<CacheEntry> cache;
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheableRequestPolicy.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheableRequestPolicy.java
index 1c46d6178..e3528230d 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheableRequestPolicy.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CacheableRequestPolicy.java
@@ -32,12 +32,14 @@ import org.apache.http.Header;
 import org.apache.http.HeaderElement;
 import org.apache.http.HttpRequest;
 import org.apache.http.ProtocolVersion;
+import org.apache.http.annotation.Immutable;
 
 /**
  * Determines if an HttpRequest is allowed to be served from the cache.
  *
  * @since 4.1
  */
+@Immutable
 public class CacheableRequestPolicy {
 
     private static final Log LOG = LogFactory.getLog(CacheableRequestPolicy.class);
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CachedHttpResponseGenerator.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CachedHttpResponseGenerator.java
index 8167cb962..004848b11 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CachedHttpResponseGenerator.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CachedHttpResponseGenerator.java
@@ -30,6 +30,7 @@ import org.apache.http.Header;
 import org.apache.http.HttpEntity;
 import org.apache.http.HttpResponse;
 import org.apache.http.HttpStatus;
+import org.apache.http.annotation.Immutable;
 import org.apache.http.entity.ByteArrayEntity;
 import org.apache.http.message.BasicHeader;
 import org.apache.http.message.BasicHttpResponse;
@@ -39,6 +40,7 @@ import org.apache.http.message.BasicHttpResponse;
  *
  * @since 4.1
  */
+@Immutable
 public class CachedHttpResponseGenerator {
 
     /**
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CachedResponseSuitabilityChecker.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CachedResponseSuitabilityChecker.java
index 442e8762a..a7d0d7889 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CachedResponseSuitabilityChecker.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/CachedResponseSuitabilityChecker.java
@@ -32,12 +32,14 @@ import org.apache.http.Header;
 import org.apache.http.HeaderElement;
 import org.apache.http.HttpHost;
 import org.apache.http.HttpRequest;
+import org.apache.http.annotation.Immutable;
 
 /**
  * Determines whether a given response can be cached.
  *
  * @since 4.1
  */
+@Immutable
 public class CachedResponseSuitabilityChecker {
 
     private static final Log LOG = LogFactory.getLog(CachedResponseSuitabilityChecker.class);
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ConditionalRequestBuilder.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ConditionalRequestBuilder.java
index 51bfe608e..ee97d4867 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ConditionalRequestBuilder.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ConditionalRequestBuilder.java
@@ -29,11 +29,13 @@ package org.apache.http.client.cache.impl;
 import org.apache.http.Header;
 import org.apache.http.HttpRequest;
 import org.apache.http.ProtocolException;
+import org.apache.http.annotation.Immutable;
 import org.apache.http.impl.client.RequestWrapper;
 
 /**
  * @since 4.1
  */
+@Immutable
 public class ConditionalRequestBuilder {
 
     public HttpRequest buildConditionalRequest(HttpRequest request, CacheEntry cacheEntry)
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/DefaultCacheEntrySerializer.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/DefaultCacheEntrySerializer.java
index cb7f3d455..4942d9a59 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/DefaultCacheEntrySerializer.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/DefaultCacheEntrySerializer.java
@@ -32,6 +32,7 @@ import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.OutputStream;
 
+import org.apache.http.annotation.Immutable;
 import org.apache.http.client.cache.HttpCacheEntrySerializer;
 
 /**
@@ -42,6 +43,7 @@ import org.apache.http.client.cache.HttpCacheEntrySerializer;
  *
  * @since 4.1
  */
+@Immutable
 public class DefaultCacheEntrySerializer implements HttpCacheEntrySerializer<CacheEntry> {
 
     public void writeTo(CacheEntry cacheEntry, OutputStream os) throws IOException {
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/HeaderConstants.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/HeaderConstants.java
index 09a6d88ea..6fbf2c92f 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/HeaderConstants.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/HeaderConstants.java
@@ -26,9 +26,12 @@
  */
 package org.apache.http.client.cache.impl;
 
+import org.apache.http.annotation.Immutable;
+
 /**
  * @since 4.1
  */
+@Immutable
 public class HeaderConstants {
 
     public static final String GET_METHOD = "GET";
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/RequestProtocolCompliance.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/RequestProtocolCompliance.java
index aca8d9093..55f0ca151 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/RequestProtocolCompliance.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/RequestProtocolCompliance.java
@@ -37,6 +37,7 @@ import org.apache.http.HttpResponse;
 import org.apache.http.HttpStatus;
 import org.apache.http.ProtocolException;
 import org.apache.http.ProtocolVersion;
+import org.apache.http.annotation.Immutable;
 import org.apache.http.entity.AbstractHttpEntity;
 import org.apache.http.impl.client.RequestWrapper;
 import org.apache.http.message.BasicHeader;
@@ -46,6 +47,7 @@ import org.apache.http.message.BasicStatusLine;
 /**
  * @since 4.1
  */
+@Immutable
 public class RequestProtocolCompliance {
 
     public List<RequestProtocolError> requestIsFatallyNonCompliant(HttpRequest request) {
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ResponseCachingPolicy.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ResponseCachingPolicy.java
index 88cd12307..e4e396943 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ResponseCachingPolicy.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ResponseCachingPolicy.java
@@ -33,6 +33,7 @@ import org.apache.http.HeaderElement;
 import org.apache.http.HttpRequest;
 import org.apache.http.HttpResponse;
 import org.apache.http.HttpStatus;
+import org.apache.http.annotation.Immutable;
 import org.apache.http.impl.cookie.DateParseException;
 import org.apache.http.impl.cookie.DateUtils;
 
@@ -41,6 +42,7 @@ import org.apache.http.impl.cookie.DateUtils;
  *
  * @since 4.1
  */
+@Immutable
 public class ResponseCachingPolicy {
 
     private final int maxObjectSizeBytes;
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ResponseProtocolCompliance.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ResponseProtocolCompliance.java
index ee9e31cda..19332aa5e 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ResponseProtocolCompliance.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/ResponseProtocolCompliance.java
@@ -33,6 +33,7 @@ import org.apache.http.HttpRequest;
 import org.apache.http.HttpResponse;
 import org.apache.http.HttpStatus;
 import org.apache.http.ProtocolVersion;
+import org.apache.http.annotation.Immutable;
 import org.apache.http.client.ClientProtocolException;
 import org.apache.http.impl.client.RequestWrapper;
 import org.apache.http.impl.cookie.DateUtils;
@@ -40,6 +41,7 @@ import org.apache.http.impl.cookie.DateUtils;
 /**
  * @since 4.1
  */
+@Immutable
 public class ResponseProtocolCompliance {
 
     public void ensureProtocolCompliance(HttpRequest request, HttpResponse response)
diff --git a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/URIExtractor.java b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/URIExtractor.java
index 20bf7fcb3..90c81f523 100644
--- a/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/URIExtractor.java
+++ b/httpclient-cache/src/main/java/org/apache/http/client/cache/impl/URIExtractor.java
@@ -36,10 +36,12 @@ import org.apache.http.Header;
 import org.apache.http.HeaderElement;
 import org.apache.http.HttpHost;
 import org.apache.http.HttpRequest;
+import org.apache.http.annotation.Immutable;
 
 /**
  * @since 4.1
  */
+@Immutable
 public class URIExtractor {
 
     public String getURI(HttpHost host, HttpRequest req) {