diff --git a/lib/spack/llnl/util/filesystem.py b/lib/spack/llnl/util/filesystem.py
index 2478f5c1592..4cf99163e06 100644
--- a/lib/spack/llnl/util/filesystem.py
+++ b/lib/spack/llnl/util/filesystem.py
@@ -93,7 +93,7 @@ def groupid_to_group(x):
 
         try:
             for line in fileinput.input(filename, inplace=True):
-                print(re.sub(regex, repl, line.rstrip()))
+                print(re.sub(regex, repl, line.rstrip('\n')))
         except:
             # clean up the original file on failure.
             shutil.move(backup_filename, filename)