diff --git a/ice-9/format.scm b/ice-9/format.scm
index b116687b8..922f62be4 100644
--- a/ice-9/format.scm
+++ b/ice-9/format.scm
@@ -614,8 +614,7 @@
 	       (case modifier
 		 ((colon)
 		  (if (not max-iterations) (set! max-iterations 1)))
-		 ((colon-at at) (format:error "illegal modifier"))
-		 (else (if (not max-iterations) (set! max-iterations 100))))
+		 ((colon-at at) (format:error "illegal modifier")))
 	       (if (not (null? params))
 		   (format:error "no parameters allowed in ~~}"))
 	       (if (zero? iteration-nest)
@@ -637,7 +636,8 @@
 					    (list-tail args arg-pos))))
 			     (i 0 (+ i 1)))
 			    ((or (>= arg-pos args-len)
-				 (>= i max-iterations))))))
+				 (and max-iterations
+				      (>= i max-iterations)))))))
 		     ((sublists)
 		      (let ((args (next-arg))
 			    (args-len 0))
@@ -646,7 +646,8 @@
 			(set! args-len (length args))
 			(do ((arg-pos 0 (+ arg-pos 1)))
 			    ((or (>= arg-pos args-len)
-				 (>= arg-pos max-iterations)))
+				 (and max-iterations
+				      (>= arg-pos max-iterations))))
 			  (let ((sublist (list-ref args arg-pos)))
 			    (if (not (list? sublist))
 				(format:error
@@ -663,7 +664,8 @@
 						   args arg-pos))))
 				   (i 0 (+ i 1)))
 				  ((or (>= arg-pos args-len)
-				       (>= i max-iterations))
+				       (and max-iterations
+					    (>= i max-iterations)))
 				   arg-pos))))
 			(add-arg-pos usedup-args)))
 		     ((rest-sublists)
@@ -672,7 +674,8 @@
 			     (usedup-args
 			      (do ((arg-pos 0 (+ arg-pos 1)))
 				  ((or (>= arg-pos args-len)
-				       (>= arg-pos max-iterations))
+				       (and max-iterations
+					    (>= arg-pos max-iterations)))
 				   arg-pos)
 				(let ((sublist (list-ref args arg-pos)))
 				  (if (not (list? sublist))