diff --git a/src/nvim/path.c b/src/nvim/path.c
index 4c16adde4c..80890acb7d 100644
--- a/src/nvim/path.c
+++ b/src/nvim/path.c
@@ -1538,6 +1538,13 @@ void simplify_filename(char *filename)
     } while (vim_ispathsep(*p));
   }
   char *start = p;        // remember start after "c:/" or "/" or "///"
+#ifdef UNIX
+  // Posix says that "//path" is unchanged but "///path" is "/path".
+  if (start > filename + 2) {
+    STRMOVE(filename + 1, p);
+    start = p = filename + 1;
+  }
+#endif
 
   do {
     // At this point "p" is pointing to the char following a single "/"
diff --git a/test/old/testdir/test_functions.vim b/test/old/testdir/test_functions.vim
index 143fdc8073..2bf2f78aa0 100644
--- a/test/old/testdir/test_functions.vim
+++ b/test/old/testdir/test_functions.vim
@@ -383,6 +383,10 @@ func Test_simplify()
   call assert_equal('/',           simplify('/.'))
   call assert_equal('/',           simplify('/..'))
   call assert_equal('/...',        simplify('/...'))
+  call assert_equal('//path',      simplify('//path'))
+  call assert_equal('/path',       simplify('///path'))
+  call assert_equal('/path',       simplify('////path'))
+
   call assert_equal('./dir/file',  './dir/file'->simplify())
   call assert_equal('./dir/file',  simplify('.///dir//file'))
   call assert_equal('./dir/file',  simplify('./dir/./file'))
@@ -2069,6 +2073,7 @@ endfunc
 
 " Test for the inputdialog() function
 func Test_inputdialog()
+  set timeout timeoutlen=10
   if has('gui_running')
     call assert_fails('let v=inputdialog([], "xx")', 'E730:')
     call assert_fails('let v=inputdialog("Q", [])', 'E730:')
@@ -2078,6 +2083,7 @@ func Test_inputdialog()
     call feedkeys(":let v=inputdialog('Q:', 'xx', 'yy')\<CR>\<Esc>", 'xt')
     call assert_equal('yy', v)
   endif
+  set timeout& timeoutlen&
 endfunc
 
 " Test for inputlist()