diff --git a/Documentation/git-worktree.adoc b/Documentation/git-worktree.adoc
index d74ad7b0e9..fbf8426cd9 100644
--- a/Documentation/git-worktree.adoc
+++ b/Documentation/git-worktree.adoc
@@ -131,7 +131,13 @@ with linked worktrees if you move the main worktree manually.)
 
 `prune`::
 
-Prune worktree information in `$GIT_DIR/worktrees`.
+Remove worktree information in `$GIT_DIR/worktrees` for worktrees
+whose working trees are missing.  Useful after manually removing
+a working tree that is no longer needed (but use "git worktree
+remove" next time you want to do so).  Also, if you _moved_ a
+working tree elsewhere causing the worktree information to become
+dangling, see "git worktree repair" to reconnect the worktree to
+the new working tree location.
 
 `remove`::
 
@@ -271,7 +277,7 @@ mismatch, even if the links are correct.
 With `list`, output additional information about worktrees (see below).
 
 `--expire <time>`::
-	With `prune`, only expire unused worktrees older than _<time>_.
+	With `prune`, only prune missing worktrees if older than _<time>_.
 +
 With `list`, annotate missing worktrees as prunable if they are older than
 _<time>_.
diff --git a/builtin/worktree.c b/builtin/worktree.c
index fbdaf2eb2e..3d6547c23b 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -252,7 +252,7 @@ static int prune(int ac, const char **av, const char *prefix,
 		OPT__DRY_RUN(&show_only, N_("do not remove, show only")),
 		OPT__VERBOSE(&verbose, N_("report pruned working trees")),
 		OPT_EXPIRY_DATE(0, "expire", &expire,
-				N_("expire working trees older than <time>")),
+				N_("prune missing working trees older than <time>")),
 		OPT_END()
 	};
 
@@ -1070,7 +1070,7 @@ static int list(int ac, const char **av, const char *prefix,
 		OPT_BOOL(0, "porcelain", &porcelain, N_("machine-readable output")),
 		OPT__VERBOSE(&verbose, N_("show extended annotations and reasons, if available")),
 		OPT_EXPIRY_DATE(0, "expire", &expire,
-				N_("add 'prunable' annotation to worktrees older than <time>")),
+				N_("add 'prunable' annotation to missing worktrees older than <time>")),
 		OPT_SET_INT('z', NULL, &line_terminator,
 			    N_("terminate records with a NUL character"), '\0'),
 		OPT_END()