diff --git a/src/common/mac/HTTPMultipartUpload.m b/src/common/mac/HTTPMultipartUpload.m
index 4b008f5c..76f38f8a 100644
--- a/src/common/mac/HTTPMultipartUpload.m
+++ b/src/common/mac/HTTPMultipartUpload.m
@@ -32,6 +32,8 @@
 
 @interface HTTPMultipartUpload(PrivateMethods)
 - (NSString *)multipartBoundary;
+// Each of the following methods will append the starting multipart boundary,
+// but not the ending one.
 - (NSData *)formDataForKey:(NSString *)key value:(NSString *)value;
 - (NSData *)formDataForFileContents:(NSData *)contents name:(NSString *)name;
 - (NSData *)formDataForFile:(NSString *)file name:(NSString *)name;
@@ -67,11 +69,9 @@
   NSString *fmt = @"--%@\r\nContent-Disposition: form-data; name=\"%@\"; "
     "filename=\"minidump.dmp\"\r\nContent-Type: application/octet-stream\r\n\r\n";
   NSString *pre = [NSString stringWithFormat:fmt, boundary_, escaped];
-  NSString *post = [NSString stringWithFormat:@"\r\n--%@\r\n", boundary_];
 
   [data appendData:[pre dataUsingEncoding:NSUTF8StringEncoding]];
   [data appendData:contents];
-  [data appendData:[post dataUsingEncoding:NSUTF8StringEncoding]];
 
   return data;
 }