diff --git a/src/blob.c b/src/blob.c
index 57fe58b..2138ac0 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -412,16 +412,19 @@
  * "remove({blob})" function
  */
     void
-blob_remove(typval_T *argvars, typval_T *rettv)
+blob_remove(typval_T *argvars, typval_T *rettv, char_u *arg_errmsg)
 {
+    blob_T	*b = argvars[0].vval.v_blob;
     int		error = FALSE;
     long	idx;
     long	end;
 
+    if (b != NULL && value_check_lock(b->bv_lock, arg_errmsg, TRUE))
+	return;
+
     idx = (long)tv_get_number_chk(&argvars[1], &error);
     if (!error)
     {
-	blob_T  *b = argvars[0].vval.v_blob;
 	int	len = blob_len(b);
 	char_u  *p;
 
diff --git a/src/errors.h b/src/errors.h
index 44b2828..942cf65 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -366,7 +366,8 @@
 	INIT(= N_("E1096: Returning a value in a function without a return type"));
 EXTERN char e_line_incomplete[]
 	INIT(= N_("E1097: Line incomplete"));
-// E1098 unused
+EXTERN char e_string_list_or_blob_required[]
+	INIT(= N_("E1098: String, List or Blob required"));
 EXTERN char e_unknown_error_while_executing_str[]
 	INIT(= N_("E1099: Unknown error while executing %s"));
 EXTERN char e_cannot_declare_script_variable_in_function[]
diff --git a/src/eval.c b/src/eval.c
index 3688176..550fe8e 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1749,7 +1749,7 @@
 	    }
 	    else
 	    {
-		emsg(_(e_listreq));
+		emsg(_(e_string_list_or_blob_required));
 		clear_tv(&tv);
 	    }
 	}
diff --git a/src/list.c b/src/list.c
index c65c8df..bf24cee 100644
--- a/src/list.c
+++ b/src/list.c
@@ -2817,45 +2817,49 @@
 
     if (argvars[0].v_type == VAR_BLOB)
     {
-	int	    val, len;
-	char_u	    *p;
+	blob_T	*b = argvars[0].vval.v_blob;
 
-	if (argvars[0].vval.v_blob == NULL)
+	if (b == NULL)
 	{
 	    if (in_vim9script())
 		emsg(_(e_cannot_add_to_null_blob));
-	    return;
 	}
-
-	len = blob_len(argvars[0].vval.v_blob);
-	if (argvars[2].v_type != VAR_UNKNOWN)
+	else if (!value_check_lock(b->bv_lock,
+				     (char_u *)N_("insert() argument"), TRUE))
 	{
-	    before = (long)tv_get_number_chk(&argvars[2], &error);
-	    if (error)
-		return;		// type error; errmsg already given
-	    if (before < 0 || before > len)
+	    int		val, len;
+	    char_u	*p;
+
+	    len = blob_len(b);
+	    if (argvars[2].v_type != VAR_UNKNOWN)
 	    {
-		semsg(_(e_invarg2), tv_get_string(&argvars[2]));
+		before = (long)tv_get_number_chk(&argvars[2], &error);
+		if (error)
+		    return;		// type error; errmsg already given
+		if (before < 0 || before > len)
+		{
+		    semsg(_(e_invarg2), tv_get_string(&argvars[2]));
+		    return;
+		}
+	    }
+	    val = tv_get_number_chk(&argvars[1], &error);
+	    if (error)
+		return;
+	    if (val < 0 || val > 255)
+	    {
+		semsg(_(e_invarg2), tv_get_string(&argvars[1]));
 		return;
 	    }
-	}
-	val = tv_get_number_chk(&argvars[1], &error);
-	if (error)
-	    return;
-	if (val < 0 || val > 255)
-	{
-	    semsg(_(e_invarg2), tv_get_string(&argvars[1]));
-	    return;
-	}
 
-	if (ga_grow(&argvars[0].vval.v_blob->bv_ga, 1) == FAIL)
-	    return;
-	p = (char_u *)argvars[0].vval.v_blob->bv_ga.ga_data;
-	mch_memmove(p + before + 1, p + before, (size_t)len - before);
-	*(p + before) = val;
-	++argvars[0].vval.v_blob->bv_ga.ga_len;
+	    if (ga_grow(&b->bv_ga, 1) == FAIL)
+		return;
+	    p = (char_u *)b->bv_ga.ga_data;
+	    mch_memmove(p + before + 1, p + before, (size_t)len - before);
+	    *(p + before) = val;
+	    ++b->bv_ga.ga_len;
 
-	copy_tv(&argvars[0], rettv);
+	    copy_tv(&argvars[0], rettv);
+	}
     }
     else if (argvars[0].v_type != VAR_LIST)
 	semsg(_(e_listblobarg), "insert()");
@@ -2917,7 +2921,7 @@
     if (argvars[0].v_type == VAR_DICT)
 	dict_remove(argvars, rettv, arg_errmsg);
     else if (argvars[0].v_type == VAR_BLOB)
-	blob_remove(argvars, rettv);
+	blob_remove(argvars, rettv, arg_errmsg);
     else if (argvars[0].v_type == VAR_LIST)
 	list_remove(argvars, rettv, arg_errmsg);
     else
diff --git a/src/proto/blob.pro b/src/proto/blob.pro
index 157f15b..5d80463 100644
--- a/src/proto/blob.pro
+++ b/src/proto/blob.pro
@@ -18,5 +18,5 @@
 int check_blob_index(long bloblen, varnumber_T n1, int quiet);
 int check_blob_range(long bloblen, varnumber_T n1, varnumber_T n2, int quiet);
 int blob_set_range(blob_T *dest, long n1, long n2, typval_T *src);
-void blob_remove(typval_T *argvars, typval_T *rettv);
+void blob_remove(typval_T *argvars, typval_T *rettv, char_u *arg_errmsg);
 /* vim: set ft=c : */
diff --git a/src/testdir/test_blob.vim b/src/testdir/test_blob.vim
index b41ca78..d56c4f7 100644
--- a/src/testdir/test_blob.vim
+++ b/src/testdir/test_blob.vim
@@ -428,6 +428,23 @@
       call remove(test_null_blob(), 1, 2)
   END
   call CheckLegacyAndVim9Failure(lines, 'E979:')
+
+  let lines =<< trim END
+      let b = 0zDEADBEEF
+      lockvar b
+      call remove(b, 0)
+      unlockvar b
+  END
+  call CheckScriptFailure(lines, 'E741:')
+
+  " can only check at script level, not in a :def function
+  let lines =<< trim END
+      vim9script
+      var b = 0zDEADBEEF
+      lockvar b
+      remove(b, 0)
+  END
+  call CheckScriptFailure(lines, 'E741:')
 endfunc
 
 func Test_blob_read_write()
@@ -543,6 +560,22 @@
       insert(test_null_blob(), 0x33)
   END
   call CheckDefExecAndScriptFailure(lines, 'E1131:')
+
+  let lines =<< trim END
+      let b = 0zDEADBEEF
+      lockvar b
+      call insert(b, 3)
+      unlockvar b
+  END
+  call CheckScriptFailure(lines, 'E741:')
+
+  let lines =<< trim END
+      vim9script
+      var b = 0zDEADBEEF
+      lockvar b
+      insert(b, 3)
+  END
+  call CheckScriptFailure(lines, 'E741:')
 endfunc
 
 func Test_blob_reverse()
diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index 1fbb74b..ac9589d 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -65,9 +65,9 @@
 endfunc
 
 func Test_for_invalid()
-  call assert_fails("for x in 99", 'E714:')
-  call assert_fails("for x in function('winnr')", 'E714:')
-  call assert_fails("for x in {'a': 9}", 'E714:')
+  call assert_fails("for x in 99", 'E1098:')
+  call assert_fails("for x in function('winnr')", 'E1098:')
+  call assert_fails("for x in {'a': 9}", 'E1098:')
 
   if 0
     /1/5/2/s/\n
diff --git a/src/version.c b/src/version.c
index 35bb391..1b1f7a6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3284,
+/**/
     3283,
 /**/
     3282,