diff --git a/osaca/get_instr.py b/osaca/get_instr.py
index 891c8f4..98f39bf 100755
--- a/osaca/get_instr.py
+++ b/osaca/get_instr.py
@@ -72,7 +72,8 @@ def set_counter_char(line):
     elif(numSpaces == 0 and numTabs != 0):
         cntChar = '\t'
     else:
-        raise NotImplementedError("Indentation of code is only supported for whitespaces and tabs.")
+        err_msg = 'Indentation of code is only supported for whitespaces and tabs.'
+        raise NotImplementedError(err_msg)
 
 
 def check_instr(instr):