diff --git a/Doc/lib/libtraceback.tex b/Doc/lib/libtraceback.tex
index 1d84763..366421a 100644
--- a/Doc/lib/libtraceback.tex
+++ b/Doc/lib/libtraceback.tex
@@ -144,9 +144,9 @@
         exec source in envdir
     except:
         print "Exception in user code:"
-	print '-'*60
+        print '-'*60
         traceback.print_exc(file=sys.stdout)
-	print '-'*60
+        print '-'*60
 
 envdir = {}
 while 1: