diff --git a/lib/commit.tcl b/lib/commit.tcl
index 89eb8c7b739131..0ffc3ec0284024 100644
--- a/lib/commit.tcl
+++ b/lib/commit.tcl
@@ -386,7 +386,9 @@ proc commit_committree {fd_wt curHEAD msg_p} {
 		set fd_ot [git_read [list cat-file commit $PARENT]]
 		fconfigure $fd_ot -encoding iso8859-1
 		set old_tree [gets $fd_ot]
-		close $fd_ot
+		# Ignore a failure at close time: on Windows the child may
+		# die writing the unread tail of the commit object.
+		catch {close $fd_ot}
 
 		if {[string equal -length 5 {tree } $old_tree]
 			&& [string length $old_tree] == [expr {$hashlength + 5}]} {