diff --git a/lisp/isearch.el b/lisp/isearch.el
index a0aa250c4b..69c553deda 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -965,10 +965,6 @@ isearch-hidden
 ;; The value of input-method-function when isearch is invoked.
 (defvar isearch-input-method-function nil)
 
-;; A flag to tell if input-method-function is locally bound when
-;; isearch is invoked.
-(defvar isearch-input-method-local-p nil)
-
 (defvar isearch--saved-overriding-local-map nil)
 
 ;; Minor-mode-alist changes - kind of redundant with the
@@ -1238,7 +1234,6 @@ isearch-mode
 	search-ring-yank-pointer nil
 	isearch-opened-overlays nil
 	isearch-input-method-function input-method-function
-	isearch-input-method-local-p (local-variable-p 'input-method-function)
 	regexp-search-ring-yank-pointer nil
 
 	isearch-pre-scroll-point nil
@@ -1259,8 +1254,6 @@ isearch-mode
   ;; We must bypass input method while reading key.  When a user type
   ;; printable character, appropriate input method is turned on in
   ;; minibuffer to read multibyte characters.
-  (or isearch-input-method-local-p
-      (make-local-variable 'input-method-function))
   (setq input-method-function nil)
 
   (looking-at "")
@@ -1418,8 +1411,8 @@ isearch-done
 	(set-window-group-start (selected-window) found-start t))))
 
   (setq isearch-mode nil)
-  (if isearch-input-method-local-p
-      (setq input-method-function isearch-input-method-function)
+  (if isearch-input-method-function
+      (setq-local input-method-function isearch-input-method-function)
     (kill-local-variable 'input-method-function))
 
   (if isearch-tool-bar-old-map
diff --git a/lisp/international/isearch-x.el b/lisp/international/isearch-x.el
index f50f86a035..94716721b5 100644
--- a/lisp/international/isearch-x.el
+++ b/lisp/international/isearch-x.el
@@ -35,8 +35,7 @@ isearch-toggle-specified-input-method
   (interactive)
   (let ((overriding-terminal-local-map nil))
     (toggle-input-method t))
-  (setq isearch-input-method-function input-method-function
-	isearch-input-method-local-p t)
+  (setq isearch-input-method-function input-method-function)
   (setq input-method-function nil)
   (isearch-update))
 
@@ -46,8 +45,7 @@ isearch-toggle-input-method
   (interactive)
   (let ((overriding-terminal-local-map nil))
     (toggle-input-method))
-  (setq isearch-input-method-function input-method-function
-	isearch-input-method-local-p t)
+  (setq isearch-input-method-function input-method-function)
   (setq input-method-function nil)
   (isearch-update))
 
@@ -57,8 +55,7 @@ isearch-transient-input-method
   (interactive)
   (let ((overriding-terminal-local-map nil))
     (activate-transient-input-method))
-  (setq isearch-input-method-function input-method-function
-	isearch-input-method-local-p t)
+  (setq isearch-input-method-function input-method-function)
   (setq input-method-function nil)
   (isearch-update))
 
diff --git a/lisp/language/korea-util.el b/lisp/language/korea-util.el
index 3821785da7..13cd6a015d 100644
--- a/lisp/language/korea-util.el
+++ b/lisp/language/korea-util.el
@@ -70,8 +70,7 @@ isearch-toggle-korean-input-method
   (interactive)
   (let ((overriding-terminal-local-map nil))
     (toggle-korean-input-method))
-  (setq isearch-input-method-function input-method-function
-	isearch-input-method-local-p t)
+  (setq isearch-input-method-function input-method-function)
   (setq input-method-function nil)
   (isearch-update))
 
@@ -79,8 +78,7 @@ isearch-hangul-switch-symbol-ksc
   (interactive)
   (let ((overriding-terminal-local-map nil))
     (quail-hangul-switch-symbol-ksc))
-  (setq isearch-input-method-function input-method-function
-	isearch-input-method-local-p t)
+  (setq isearch-input-method-function input-method-function)
   (setq input-method-function nil)
   (isearch-update))
 
@@ -88,8 +86,7 @@ isearch-hangul-switch-hanja
   (interactive)
   (let ((overriding-terminal-local-map nil))
     (quail-hangul-switch-hanja))
-  (setq isearch-input-method-function input-method-function
-	isearch-input-method-local-p t)
+  (setq isearch-input-method-function input-method-function)
   (setq input-method-function nil)
   (isearch-update))