diff --git a/AFNetworking/AFHTTPClient.m b/AFNetworking/AFHTTPClient.m
index d5af72c..0596022 100644
--- a/AFNetworking/AFHTTPClient.m
+++ b/AFNetworking/AFHTTPClient.m
@@ -93,7 +93,7 @@ static NSString * AFBase64EncodedStringFromString(NSString *string) {
     return [[[NSString alloc] initWithData:mutableData encoding:NSASCIIStringEncoding] autorelease];
 }
 
-NSString * AFPercentEscapedQueryStringPairMemberFromStringWithEncoding(NSString *string, NSStringEncoding encoding) {
+static NSString * AFPercentEscapedQueryStringPairMemberFromStringWithEncoding(NSString *string, NSStringEncoding encoding) {
     // Escape characters that are legal in URIs, but have unintentional semantic significance when used in a query string parameter
     static NSString * const kAFLegalCharactersToBeEscaped = @":/.?&=;+!@$()~";