diff --git a/Doc/texinputs/fncychap.sty b/Doc/texinputs/fncychap.sty
index 4e693b8..b0d7b76 100644
--- a/Doc/texinputs/fncychap.sty
+++ b/Doc/texinputs/fncychap.sty
@@ -1,3 +1,6 @@
+%%% Derived from the original fncychap.sty,
+%%% but changed ``TWELV'' to ``TWELVE''.
+
 %%% Copyright   Ulf A. Lindgren
 %%%             Department of Applied Electronics
 %%%             Chalmers University of Technology
@@ -346,7 +349,7 @@
         ZERO\else{}\fi
     \or ONE\or TWO\or THREE\or FOUR\or FIVE
     \or SIX\or SEVEN\or EIGHT\or NINE\or TEN
-    \or ELEVEN\or TWELV\or THIRTEEN\or FOURTEEN\or FIFTEEN
+    \or ELEVEN\or TWELVE\or THIRTEEN\or FOURTEEN\or FIFTEEN
     \or SIXTEEN\or SEVENTEEN\or EIGHTEEN\or NINETEEN\fi
 }