diff --git a/src/backend/modern.lisp b/src/backend/modern.lisp
index 8d34192..dc848ef 100644
--- a/src/backend/modern.lisp
+++ b/src/backend/modern.lisp
@@ -162,23 +162,17 @@ as a fallback when a keyword is not in *named-colors*.")
   (values))
 
 (defmethod backend-size ((b modern-backend))
-  (or ;; ioctl on fd 0 (stdin) — the parent's own terminal, which IS
-      ;; the real controlling terminal when running from a shell.
-      (multiple-value-bind (cols rows)
-          (ignore-errors
-            (let ((winsize (sb-alien:make-alien sb-alien:unsigned-short 4)))
-              (unwind-protect
-                   (let ((ok (sb-unix:unix-ioctl 0 21523
-                                                 (sb-alien:alien-sap winsize))))
-                     (when ok
-                       (let ((c (sb-alien:deref winsize 1))
-                             (r (sb-alien:deref winsize 0)))
-                         (when (and c r (> c 0) (> r 0))
-                           (values c r)))))
-                (sb-alien:free-alien winsize))))
+  ;; MY_TERM_COLS/MY_TERM_ROWS — set by the passepartout script
+  ;; before exec sbcl. Check FIRST with return-from so both
+  ;; values (cols and rows) are preserved (or discards secondaries).
+  (let ((cstr (sb-ext:posix-getenv "MY_TERM_COLS"))
+        (rstr (sb-ext:posix-getenv "MY_TERM_ROWS")))
+    (when (and cstr rstr)
+      (let ((cols (parse-integer cstr :junk-allowed t))
+            (rows (parse-integer rstr :junk-allowed t)))
         (when (and cols rows (> cols 0) (> rows 0))
-          (values cols rows)))
-      ;; ioctl on stdout fd — fast, correct after SIGWINCH at runtime.
+          (return-from backend-size (values cols rows))))))
+  (or
       (multiple-value-bind (cols rows)
           (ignore-errors
             (let* ((winsize (sb-alien:make-alien sb-alien:unsigned-short 4)))
@@ -204,16 +198,7 @@ as a fallback when a keyword is not in *named-colors*.")
                        (let ((cols (sb-alien:deref winsize 1))
                              (rows (sb-alien:deref winsize 0)))
                          (values cols rows)))))
-              (sb-unix:unix-close tty-fd)))))
-      ;; MY_TERM_COLS/MY_TERM_LINES — set by the passepartout script
-      ;; before exec sbcl. SBCL strips COLUMNS/LINES but leaves these.
-      (ignore-errors
-        (let* ((cstr (sb-ext:posix-getenv "MY_TERM_COLS"))
-               (rstr (sb-ext:posix-getenv "MY_TERM_LINES"))
-               (cols (when cstr (parse-integer cstr :junk-allowed t)))
-               (rows (when rstr (parse-integer rstr :junk-allowed t))))
-          (when (and cols rows (> cols 0) (> rows 0))
-            (values cols rows))))
+               (sb-unix:unix-close tty-fd)))))
       (values 80 24)))
 
 (defmethod backend-write ((b modern-backend) string)
diff --git a/src/backend/simple.lisp b/src/backend/simple.lisp
index d6df6d5..c21fc73 100644
--- a/src/backend/simple.lisp
+++ b/src/backend/simple.lisp
@@ -22,6 +22,15 @@
   (values))
 
 (defmethod backend-size ((b simple-backend))
+  ;; MY_TERM_COLS/MY_TERM_ROWS — set by the passepartout script.
+  ;; Check with return-from to preserve both values.
+  (let ((cstr (sb-ext:posix-getenv "MY_TERM_COLS"))
+        (rstr (sb-ext:posix-getenv "MY_TERM_ROWS")))
+    (when (and cstr rstr)
+      (let ((cols (parse-integer cstr :junk-allowed t))
+            (rows (parse-integer rstr :junk-allowed t)))
+        (when (and cols rows (> cols 0) (> rows 0))
+          (return-from backend-size (values cols rows))))))
   (or ;; ioctl on fd 0 (stdin) — the parent's own terminal.
       (multiple-value-bind (cols rows)
           (ignore-errors
@@ -62,15 +71,7 @@
                        (values (sb-alien:deref winsize 1)
                                (sb-alien:deref winsize 0))))
                    (sb-alien:free-alien winsize))
-               (sb-unix:unix-close tty-fd)))))
-      ;; MY_TERM_COLS/MY_TERM_LINES — set by the passepartout script.
-      (ignore-errors
-        (let* ((cstr (sb-ext:posix-getenv "MY_TERM_COLS"))
-               (rstr (sb-ext:posix-getenv "MY_TERM_LINES"))
-               (cols (when cstr (parse-integer cstr :junk-allowed t)))
-               (rows (when rstr (parse-integer rstr :junk-allowed t))))
-          (when (and cols rows (> cols 0) (> rows 0))
-            (values cols rows))))
+                (sb-unix:unix-close tty-fd)))))
       (values 80 24)))
 
 (defmethod backend-write ((b simple-backend) string)