diff --git a/doc/Guidebook.mn b/doc/Guidebook.mn
index f79c5ad3c..38f6ba8fb 100644
--- a/doc/Guidebook.mn
+++ b/doc/Guidebook.mn
@@ -2359,7 +2359,7 @@ damage can be repaired.  Some types of armor may inhibit spell casting.
 The
 .op nudist
 option can be set (prior to game start) to attempt to play the entire
-game without wearing any armor (a self-imposed challange which is
+game without wearing any armor (a self-imposed challenge which is
 extremely difficult to accomplish).
 .pg
 The commands to use armor are \(oqW\(cq (wear) and \(oqT\(cq (take off).
diff --git a/doc/Guidebook.tex b/doc/Guidebook.tex
index a5f44543f..5c95aeae1 100644
--- a/doc/Guidebook.tex
+++ b/doc/Guidebook.tex
@@ -2557,7 +2557,7 @@ damage can be repaired.  Some types of armor may inhibit spell casting.
 %.pg
 The {\it nudist\/}
 option can be set (prior to game start) to attempt to play the entire
-game without wearing any armor (a self-imposed challange which is
+game without wearing any armor (a self-imposed challenge which is
 extremely difficult to accomplish).
 
 %.pg