diff --git a/AFNetworking/AFHTTPClient.m b/AFNetworking/AFHTTPClient.m
index 53d90ef..144967d 100644
--- a/AFNetworking/AFHTTPClient.m
+++ b/AFNetworking/AFHTTPClient.m
@@ -93,9 +93,10 @@ static NSString * AFBase64EncodedStringFromString(NSString *string) {
 }
 
 NSString * AFURLEncodedStringFromStringWithEncoding(NSString *string, NSStringEncoding encoding) {
-    static NSString * const kAFLegalCharactersToBeEscaped = @"?!@#$^&%*+=,:;'\"`<>()[]{}/\\|~ ";
+    // Escape characters that are legal in URIs, but have unintentional semantic significance when used in a query string parameter
+    static NSString * const kAFLegalCharactersToBeEscaped = @":/.?&=;+!@$()~";
     
-	return [(NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)string, NULL, (CFStringRef)kAFLegalCharactersToBeEscaped, CFStringConvertNSStringEncodingToEncoding(encoding)) autorelease];
+    return [(NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)string, NULL, (CFStringRef)kAFLegalCharactersToBeEscaped, CFStringConvertNSStringEncodingToEncoding(encoding)) autorelease];
 }
 
 #pragma mark -