diff --git a/lib/srfi/166/column.scm b/lib/srfi/166/column.scm
index 33308ba1..7b71ea2d 100644
--- a/lib/srfi/166/column.scm
+++ b/lib/srfi/166/column.scm
@@ -312,7 +312,7 @@
 
 ;; break lines only, don't join short lines or justify
 (define (wrapped/char . ls)
-  (fn ((orig-output output) width string-width)
+  (fn ((orig-output output) width string-width substring/width)
     (define (kons-in-line str)
       (fn (col)
         (let ((len ((or string-width string-length) str))
@@ -326,9 +326,9 @@
             (each
              ;; TODO: when splitting by string-width, substring needs
              ;; to be provided
-             (orig-output (substring str 0 space))
+             (orig-output (substring/width str 0 space))
              (orig-output "\n")
-             (fn () (kons-in-line (substring str space len)))))))))
+             (fn () (kons-in-line (substring/width str space len)))))))))
     (with ((output
             (lambda (str)
               (let ((end (string-cursor-end str)))
@@ -411,7 +411,7 @@
 
 (define (wrapped/list ls)
   (fn (width string-width pad-char)
-    (joined/suffix
+    (joined
      (lambda (ls) (joined displayed ls pad-char))
      (reverse
       (wrap-fold-words ls '() width (or string-width string-length) cons))
diff --git a/lib/srfi/166/test.sld b/lib/srfi/166/test.sld
index 1cdb08f4..d1719edf 100644
--- a/lib/srfi/166/test.sld
+++ b/lib/srfi/166/test.sld
@@ -281,6 +281,8 @@
       (test "1.2 µm" (show #f (numeric/si 1.23e-6 1000 " ") "m"))
 
       (test "1,234,567" (show #f (numeric/comma 1234567)))
+      (test "1,234,567" (show #f (numeric/comma 1234567 3)))
+      (test "123,4567" (show #f (numeric/comma 1234567 4)))
 
       (test "1.23" (show #f (numeric/fitted 4 1.2345 10 2)))
       (test "1.00" (show #f (numeric/fitted 4 1 10 2)))
@@ -606,9 +608,9 @@
                                        "abc\ndef\n")
                                  (list displayed "123\n456\n"))))
 
-      (test "hello\nworld\n"
+      (test "hello\nworld"
           (show #f (with ((width 8)) (wrapped "hello world"))))
-      (test "\n" (show #f (wrapped "    ")))
+      (test "" (show #f (wrapped "    ")))
 
       (test
           "The  quick
@@ -627,8 +629,7 @@ Applies KONS to each element of
 LS and the result of the previous
 application, beginning with KNIL.
 With KONS as CONS and KNIL as '(),
-equivalent to REVERSE.
-"
+equivalent to REVERSE."
           (show #f
                 (with ((width 36))
                   (wrapped "The fundamental list iterator.  Applies KONS to each element of LS and the result of the previous application, beginning with KNIL.  With KONS as CONS and KNIL as '(), equivalent to REVERSE."))))
@@ -674,6 +675,12 @@ equivalent to REVERSE.
                    (with ((width 36))
                      (wrapped "The fundamental list iterator.  Applies KONS to each element of LS and the result of the previous application, beginning with KNIL.  With KONS as CONS and KNIL as '(), equivalent to REVERSE."))))))
 
+      (test "\n" (show #f (columnar)))      ; degenerate case
+      (test "\n" (show #f (columnar "*")))  ; only infinite columns
+      (test "*\n" (show #f (columnar (each "*"))))
+
+      (test "foo" (show #f (wrapped "foo")))
+
       (test
            "(define (fold kons knil ls)          ; The fundamental list iterator.
   (let lp ((ls ls) (acc knil))       ; Applies KONS to each element of
diff --git a/lib/srfi/166/write.scm b/lib/srfi/166/write.scm
index a19853d9..7c58eae3 100644
--- a/lib/srfi/166/write.scm
+++ b/lib/srfi/166/write.scm
@@ -408,8 +408,8 @@
 
 (define (numeric/comma n . o)
   (fn ((orig-comma-rule comma-rule))
-    (with ((comma-rule (or orig-comma-rule 3)))
-      (apply numeric n o))))
+    (with ((comma-rule (if (pair? o) (car o) (or orig-comma-rule 3))))
+      (apply numeric n (if (pair? o) (cdr o) '())))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; written