diff --git a/runtime/ftplugin/java.vim b/runtime/ftplugin/java.vim
index 095e733..fa2b610 100644
--- a/runtime/ftplugin/java.vim
+++ b/runtime/ftplugin/java.vim
@@ -3,7 +3,7 @@
 " Maintainer:		Aliaksei Budavei <0x000c70 AT gmail DOT com>
 " Former Maintainer:	Dan Sharp
 " Repository:		https://github.com/zzzyxwvut/java-vim.git
-" Last Change:		2024 Apr 13
+" Last Change:		2024 Apr 18
 "			2024 Jan 14 by Vim Project (browsefilter)
 
 if exists("b:did_ftplugin") | finish | endif
@@ -22,8 +22,36 @@
 " name to / and append .java to the name, then search the path.
 setlocal includeexpr=substitute(v:fname,'\\.','/','g')
 setlocal suffixesadd=.java
-if exists("g:ftplugin_java_source_path")
-    let &l:path=g:ftplugin_java_source_path . ',' . &l:path
+
+" Clean up in case this file is sourced again.
+unlet! s:zip_func_upgradable
+
+" Documented in ":help ft-java-plugin".
+if exists("g:ftplugin_java_source_path") &&
+		\ type(g:ftplugin_java_source_path) == type("")
+    if filereadable(g:ftplugin_java_source_path)
+	if exists("#zip") &&
+		    \ g:ftplugin_java_source_path =~# '.\.\%(jar\|zip\)$'
+	    if !exists("s:zip_files")
+		let s:zip_files = {}
+	    endif
+
+	    let s:zip_files[bufnr('%')] = g:ftplugin_java_source_path
+	    let s:zip_files[0] = g:ftplugin_java_source_path
+	    let s:zip_func_upgradable = 1
+
+	    function! JavaFileTypeZipFile() abort
+		let @/ = substitute(v:fname, '\.', '\\/', 'g') . '.java'
+		return get(s:zip_files, bufnr('%'), s:zip_files[0])
+	    endfunction
+
+	    " E120 for "inex=s:JavaFileTypeZipFile()" before v8.2.3900.
+	    setlocal includeexpr=JavaFileTypeZipFile()
+	    setlocal suffixesadd<
+	endif
+    else
+	let &l:path = g:ftplugin_java_source_path . ',' . &l:path
+    endif
 endif
 
 " Set 'formatoptions' to break comment lines but not other lines,
@@ -52,6 +80,25 @@
 		\     " formatoptions< comments< commentstring< path< includeexpr<" .
 		\     " | unlet! b:browsefilter"
 
+" See ":help vim9-mix".
+if !has("vim9script")
+    let &cpo = s:save_cpo
+    unlet s:save_cpo
+    finish
+endif
+
+if exists("s:zip_func_upgradable")
+    delfunction! JavaFileTypeZipFile
+
+    def! s:JavaFileTypeZipFile(): string
+	@/ = substitute(v:fname, '\.', '\\/', 'g') .. '.java'
+	return get(zip_files, bufnr('%'), zip_files[0])
+    enddef
+
+    setlocal includeexpr=s:JavaFileTypeZipFile()
+    setlocal suffixesadd<
+endif
+
 " Restore the saved compatibility options.
 let &cpo = s:save_cpo
 unlet s:save_cpo