diff --git a/ASIHTTPRequest.m b/ASIHTTPRequest.m
index da9350fb..e3725b54 100644
--- a/ASIHTTPRequest.m
+++ b/ASIHTTPRequest.m
@@ -45,13 +45,14 @@ @implementation ASIHTTPRequest
 
 + (void)initialize
 {
-	progressLock = [[NSRecursiveLock alloc] init];
-	
-	ASIRequestTimedOutError = [[NSError errorWithDomain:NetworkRequestErrorDomain code:ASIRequestTimedOutErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"The request timed out",NSLocalizedDescriptionKey,nil]] retain];	
-	ASIAuthenticationError = [[NSError errorWithDomain:NetworkRequestErrorDomain code:ASIAuthenticationErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"Authentication needed",NSLocalizedDescriptionKey,nil]] retain];
-	ASIRequestCancelledError = [[NSError errorWithDomain:NetworkRequestErrorDomain code:ASIRequestCancelledErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"The request was cancelled",NSLocalizedDescriptionKey,nil]] retain];
-	ASIUnableToCreateRequestError = [[NSError errorWithDomain:NetworkRequestErrorDomain code:ASIUnableToCreateRequestErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"Unable to create request (bad url?)",NSLocalizedDescriptionKey,nil]] retain];
-	
+	if (self == [ASIHTTPRequest class]) {
+		progressLock = [[NSRecursiveLock alloc] init];
+		ASIRequestTimedOutError = [[NSError errorWithDomain:NetworkRequestErrorDomain code:ASIRequestTimedOutErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"The request timed out",NSLocalizedDescriptionKey,nil]] retain];	
+		ASIAuthenticationError = [[NSError errorWithDomain:NetworkRequestErrorDomain code:ASIAuthenticationErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"Authentication needed",NSLocalizedDescriptionKey,nil]] retain];
+		ASIRequestCancelledError = [[NSError errorWithDomain:NetworkRequestErrorDomain code:ASIRequestCancelledErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"The request was cancelled",NSLocalizedDescriptionKey,nil]] retain];
+		ASIUnableToCreateRequestError = [[NSError errorWithDomain:NetworkRequestErrorDomain code:ASIUnableToCreateRequestErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"Unable to create request (bad url?)",NSLocalizedDescriptionKey,nil]] retain];
+	}
+	[super initialize];
 }
 
 - (id)initWithURL:(NSURL *)newURL