2 files changed, 22 insertions, 4 deletions

diff --git a/lisp/term.el b/lisp/term.el
index 9aa4a20e36e..121a22e7933 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -3306,11 +3306,9 @@ option is enabled.  See `term-set-goto-process-mark'."
    ((eq char ?B)
     (let ((tcr (term-current-row))
           (scroll-amount (car params)))
-      (unless (= tcr (1- term-scroll-end))
+      (unless (>= tcr term-scroll-end)
         (term-down
-         (if (> (+ tcr scroll-amount) term-scroll-end)
-             (- term-scroll-end 1 tcr)
-           (max 1 scroll-amount))
+         (min (- term-scroll-end tcr) (max 1 scroll-amount))
          t))))
    ;; \E[C - cursor right (terminfo: cuf, cuf1)
    ((eq char ?C)
diff --git a/test/lisp/term-tests.el b/test/lisp/term-tests.el
index 72a9ad1ef74..ebf48d50a84 100644
--- a/test/lisp/term-tests.el
+++ b/test/lisp/term-tests.el
@@ -143,6 +143,26 @@ the first character of the line."
     (should (equal (term-test-screen-from-input width 12 strs)
                    (make-string width ?_)))))
 
+(ert-deftest term-to-margin ()
+  "Test cursor movement at the scroll margin.
+This is a reduced example from GNU nano's initial screen."
+  (let* ((width 10)
+         (x (make-string width ?x))
+         (y (make-string width ?y)))
+    (should (equal (term-test-screen-from-input
+                    width 3
+                    `("\e[1;3r"       ; Setup 3 line scrolling region.
+                      "\e[2;1H"       ; Move to 2nd last line.
+                      ,x              ; Fill with 'x'.
+                      "\r\e[1B"       ; Next line.
+                      ,y))            ; Fill with 'y'.
+                   (concat "\n" x "\n" y)))
+    ;; Same idea, but moving upwards.
+    (should (equal (term-test-screen-from-input
+                    width 3
+                    `("\e[1;3r" "\e[2;1H" ,x "\r\e[1A" ,y))
+                   (concat y "\n" x)))))
+
 (provide 'term-tests)
 
 ;;; term-tests.el ends here