Index: anti-diff.scm
===================================================================
RCS file: /sources/jacal/jacal/anti-diff.scm,v
retrieving revision 1.23
diff -u -p -r1.23 anti-diff.scm
--- anti-diff.scm	14 Mar 2020 00:39:34 -0000	1.23
+++ anti-diff.scm	24 Dec 2022 00:02:01 -0000
@@ -168,7 +168,8 @@
 	   (let ((sexp (sexp:alpha-convert (list (var:sexp var))
 					   (cano->sexp expr horner))))
 	     (define ifun (indef-integrate (sexp->math sexp) $1))
-	     (cond ((case (length args)
+	     (cond ((novalue? ifun) ifun)
+		   ((case (length args)
 		      ((3) (app* ifun lo))
 		      ((4) (app* $1-$2 (app* ifun hi) (app* ifun lo)))))))))))