diff --git a/httpclient-cache/src/main/java/org/apache/http/impl/client/cache/CacheEntryUpdater.java b/httpclient-cache/src/main/java/org/apache/http/impl/client/cache/CacheEntryUpdater.java
index 87a8f152a..f1cad47ab 100644
--- a/httpclient-cache/src/main/java/org/apache/http/impl/client/cache/CacheEntryUpdater.java
+++ b/httpclient-cache/src/main/java/org/apache/http/impl/client/cache/CacheEntryUpdater.java
@@ -44,6 +44,7 @@ import org.apache.http.client.cache.ResourceFactory;
 import org.apache.http.impl.cookie.DateParseException;
 import org.apache.http.impl.cookie.DateUtils;
 import org.apache.http.protocol.HTTP;
+import org.apache.http.util.Args;
 
 /**
  * Update a {@link HttpCacheEntry} with new or updated information based on the latest
@@ -84,8 +85,8 @@ class CacheEntryUpdater {
             Date requestDate,
             Date responseDate,
             HttpResponse response) throws IOException {
-        if (response.getStatusLine().getStatusCode() != HttpStatus.SC_NOT_MODIFIED)
-            throw new IllegalArgumentException("Response must have 304 status code");
+        Args.check(response.getStatusLine().getStatusCode() == HttpStatus.SC_NOT_MODIFIED,
+                "Response must have 304 status code");
         Header[] mergedHeaders = mergeHeaders(entry, response);
         Resource oldResource = entry.getResource();
         Resource resource = null;
diff --git a/httpclient-cache/src/main/java/org/apache/http/impl/client/cache/ResourceReference.java b/httpclient-cache/src/main/java/org/apache/http/impl/client/cache/ResourceReference.java
index 91e9a0b16..4f9ac4420 100644
--- a/httpclient-cache/src/main/java/org/apache/http/impl/client/cache/ResourceReference.java
+++ b/httpclient-cache/src/main/java/org/apache/http/impl/client/cache/ResourceReference.java
@@ -32,6 +32,7 @@ import java.lang.ref.ReferenceQueue;
 import org.apache.http.annotation.Immutable;
 import org.apache.http.client.cache.HttpCacheEntry;
 import org.apache.http.client.cache.Resource;
+import org.apache.http.util.Args;
 
 @Immutable
 class ResourceReference extends PhantomReference<HttpCacheEntry> {
@@ -40,9 +41,7 @@ class ResourceReference extends PhantomReference<HttpCacheEntry> {
 
     public ResourceReference(final HttpCacheEntry entry, final ReferenceQueue<HttpCacheEntry> q) {
         super(entry, q);
-        if (entry.getResource() == null) {
-            throw new IllegalArgumentException("Resource may not be null");
-        }
+        Args.notNull(entry.getResource(), "Resource");
         this.resource = entry.getResource();
     }