diff --git a/lisp/window.el b/lisp/window.el
index af35f9abe6..7470ffc1d3 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -5365,10 +5365,22 @@ split-window-below
   (let ((old-window (selected-window))
 	(old-point (window-point))
 	(size (and size (prefix-numeric-value size)))
-        moved-by-window-height moved new-window bottom)
-    (when (and size (< size 0) (< (- size) window-min-height))
+        line-height moved-by-window-height moved new-window bottom)
+    (cond
+     ((and size (< size 0) (< (- size) window-min-height))
       ;; `split-window' would not signal an error here.
       (error "Size of new window too small"))
+     ((and (not size)
+           (< (setq line-height (window-default-line-height))
+              (frame-char-height))
+           (>= (/ (float (window-size nil nil t)) line-height)
+               window-min-height))
+        ;; As a special case when SIZE is not specified and the
+        ;; selected window has a default line height that is smaller
+        ;; than the character height of its frame, try to split the
+        ;; window even if the resulting windows would otherwise
+        ;; violate the `window-min-height' contstraints (Bug#14825).
+      (setq size (/ (window-size) 2))))
     (setq new-window (split-window nil size))
     (unless split-window-keep-point
       (with-current-buffer (window-buffer)