diff --git a/lisp/simple.el b/lisp/simple.el
index f52bd95bf84..f76f31ad146 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -617,7 +617,8 @@ region is ignored if prefix argument is given.)"
 					  (+ (point) (length fill-prefix)))))
 	  (delete-region (point) (+ (point) (length fill-prefix))))
       (fixup-whitespace)
-      (if (and beg
+      (if (and (use-region-p)
+               beg
                (not arg)
 	       (< beg (point-at-bol)))
 	  (beginning-of-line)))))
diff --git a/test/lisp/simple-tests.el b/test/lisp/simple-tests.el
index 08e81a7fefb..d9f059c8fc2 100644
--- a/test/lisp/simple-tests.el
+++ b/test/lisp/simple-tests.el
@@ -213,6 +213,40 @@
           (should (= x 0)))
       (remove-hook 'post-self-insert-hook inc))))
 
+
+;;; `delete-indentation'
+(ert-deftest simple-delete-indentation-no-region ()
+  "delete-indentation works when no mark is set."
+  ;; interactive \r returns nil for BEG END args
+  (unwind-protect
+      (with-temp-buffer
+        (insert (concat "zero line \n"
+                        "first line \n"
+                        "second line"))
+        (delete-indentation)
+        (should (string-equal
+                 (buffer-string)
+                 (concat "zero line \n"
+                         "first line second line")))
+        )))
+
+(ert-deftest simple-delete-indentation-inactive-region ()
+  "delete-indentation ignores inactive region."
+  ;; interactive \r returns non-nil for BEG END args
+  (unwind-protect
+      (with-temp-buffer
+        (insert (concat "zero line \n"
+                        "first line \n"
+                        "second line"))
+        (push-mark (point-min) t t)
+        (deactivate-mark)
+        (delete-indentation)
+        (should (string-equal
+                 (buffer-string)
+                 (concat "zero line \n"
+                         "first line second line")))
+        )))
+
 
 ;;; `delete-trailing-whitespace'
 (ert-deftest simple-delete-trailing-whitespace--bug-21766 ()