diff --git a/astropy/units/format/generic.py b/astropy/units/format/generic.py
index 391f9607495c..dfabdb3e89b0 100644
--- a/astropy/units/format/generic.py
+++ b/astropy/units/format/generic.py
@@ -161,7 +161,7 @@ def t_FUNCNAME(t):
             return t
 
         def t_UNIT(t):
-            "%|([YZEPTGMkhdcmu\N{MICRO SIGN}npfazy]?"+r"'((?!\d)\w)+')|((?!\d)\w)+"
+            "%|([YZEPTGMkhdcmu\N{MICRO SIGN}npfazy]?'((?!\\d)\\w)+')|((?!\\d)\\w)+"
             t.value = cls._get_unit(t)
             return t