diff --git a/mozilla/tools/update-packaging/make_incremental_updates.py b/mozilla/tools/update-packaging/make_incremental_updates.py
index 2ffb4b0d7dd..52749ea01e6 100755
--- a/mozilla/tools/update-packaging/make_incremental_updates.py
+++ b/mozilla/tools/update-packaging/make_incremental_updates.py
@@ -164,7 +164,7 @@ def extract_mar(filename, work_dir):
     saved_path = os.getcwd()
     try:
         os.chdir(work_dir)
-        exec_shell_cmd("mar -x "+filename)    
+        exec_shell_cmd('mar -x "'+filename+'"')    
     finally:
         os.chdir(saved_path)
 
@@ -186,7 +186,7 @@ def create_partial_patch_for_file(from_marfile_entry, to_marfile_entry, shas, pa
             os.makedirs(patch_file_dir)
 
         # Create bzip'd patch file
-        exec_shell_cmd("mbsdiff "+from_marfile_entry.abs_path+" "+to_marfile_entry.abs_path+" "+patch_file_abs_path)
+        exec_shell_cmd('mbsdiff "'+from_marfile_entry.abs_path+'" "'+to_marfile_entry.abs_path+'" "'+patch_file_abs_path+'"')
         bzip_file(patch_file_abs_path)
 
         # Create bzip's full file