diff --git a/git-gui--askpass b/git-gui--askpass
index 4277f30..1c99ee8 100755
--- a/git-gui--askpass
+++ b/git-gui--askpass
@@ -56,6 +56,11 @@
 		}
 	}
 
+	# On Windows, force the encoding to UTF-8: it is what `git.exe` expects
+	if {$::tcl_platform(platform) eq {windows}} {
+		set ::answer [encoding convertto utf-8 $::answer]
+	}
+
 	puts $::answer
 	set ::rc 0
 }