diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index e34cd4b..f06a727 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -5058,6 +5058,7 @@
 		command		Ex command (and arguments)
 		compiler	compilers
 		cscope		|:cscope| suboptions
+		diff_buffer     |:diffget| and |:diffput| completion
 		dir		directory names
 		environment	environment variable names
 		event		autocommand events