diff --git a/kordophone/Bridge/Operations/MBIMFetchAttachmentOperation.m b/kordophone/Bridge/Operations/MBIMFetchAttachmentOperation.m
index 114afd0..b7cc8b7 100644
--- a/kordophone/Bridge/Operations/MBIMFetchAttachmentOperation.m
+++ b/kordophone/Bridge/Operations/MBIMFetchAttachmentOperation.m
@@ -54,6 +54,13 @@
         }
         
         NSString *mimeType = [transfer mimeType];
+        // It's unusual, but if this is nil, try to guess the MIME type based on the filename
+        if (!mimeType) {
+            NSString *extension = [[localPath pathExtension] lowercaseString];
+
+            // XXX: REALLY hacky
+            mimeType = [NSString stringWithFormat:@"image/%@", extension];
+        }
         response = [[MBIMDataResponse alloc] initWithData:responseData contentType:mimeType];
     } while (0);
     
diff --git a/kordophone/Bridge/Operations/Utilities/MBIMDataResponse.m b/kordophone/Bridge/Operations/Utilities/MBIMDataResponse.m
index e6ea79d..8758de0 100644
--- a/kordophone/Bridge/Operations/Utilities/MBIMDataResponse.m
+++ b/kordophone/Bridge/Operations/Utilities/MBIMDataResponse.m
@@ -25,7 +25,7 @@
 - (NSDictionary *)httpHeaders
 {
     return @{
-        @"Content-Type" : _contentType
+        @"Content-Type" : _contentType ?: @"application/octet-stream"
     };
 }