diff --git a/src/search.c b/src/search.c
index ea72ec7..35dc89b 100644
--- a/src/search.c
+++ b/src/search.c
@@ -3305,6 +3305,21 @@
 }
 
 #if defined(FEAT_FIND_ID) || defined(PROTO)
+
+/*
+ * Get line "lnum" and copy it into "buf[LSIZE]".
+ * The copy is made because the regexp may make the line invalid when using a
+ * mark.
+ */
+    static char_u *
+get_line_and_copy(linenr_T lnum, char_u *buf)
+{
+    char_u *line = ml_get(lnum);
+
+    vim_strncpy(buf, line, LSIZE - 1);
+    return buf;
+}
+
 /*
  * Find identifiers or defines in included files.
  * If p_ic && compl_status_sol() then ptr must be in lowercase.
@@ -3409,7 +3424,7 @@
 	end_lnum = curbuf->b_ml.ml_line_count;
     if (lnum > end_lnum)		// do at least one line
 	lnum = end_lnum;
-    line = ml_get(lnum);
+    line = get_line_and_copy(lnum, file_line);
 
     for (;;)
     {
@@ -3738,7 +3753,7 @@
 		    {
 			if (lnum >= end_lnum)
 			    goto exit_matched;
-			line = ml_get(++lnum);
+			line = get_line_and_copy(++lnum, file_line);
 		    }
 		    else if (vim_fgets(line = file_line,
 						      LSIZE, files[depth].fp))
@@ -3950,7 +3965,7 @@
 	{
 	    if (++lnum > end_lnum)
 		break;
-	    line = ml_get(lnum);
+	    line = get_line_and_copy(lnum, file_line);
 	}
 	already = NULL;
     }
diff --git a/src/testdir/test_tagjump.vim b/src/testdir/test_tagjump.vim
index aacfb9b..060cc3b 100644
--- a/src/testdir/test_tagjump.vim
+++ b/src/testdir/test_tagjump.vim
@@ -1290,6 +1290,17 @@
   close!
 endfunc
 
+" this was using a line from ml_get() freed by the regexp
+func Test_isearch_copy_line()
+  new
+  norm o
+  norm 0
+  0norm o
+  sil! norm bc0
+  sil! isearch \%')
+  bwipe!
+endfunc
+
 " Test for :dsearch, :dlist, :djump and :dsplit commands
 " Test for [d, ]d, [D, ]D, [ CTRL-D, ] CTRL-D and CTRL-W d commands
 func Test_macro_search()
diff --git a/src/version.c b/src/version.c
index 97ca8ce..ba8688b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -735,6 +735,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    5050,
+/**/
     5049,
 /**/
     5048,