diff --git a/src/testdir/README.txt b/src/testdir/README.txt
index c649259..b3200a4 100644
--- a/src/testdir/README.txt
+++ b/src/testdir/README.txt
@@ -54,7 +54,7 @@
 
 TO ADD A SCREEN DUMP TEST:
 
-Mostly the same as writing a new style test.  Additonally, see help on
+Mostly the same as writing a new style test.  Additionally, see help on
 "terminal-dumptest".  Put the reference dump in "dumps/Test_func_name.dump".