diff --git a/Makefile b/Makefile
index 315888f..8e89140 100644
--- a/Makefile
+++ b/Makefile
@@ -223,6 +223,7 @@ install: all
 	$(QUIET)$(INSTALL_D0)'$(DESTDIR_SQ)$(gitexecdir_SQ)' $(INSTALL_D1)
 	$(QUIET)$(INSTALL_X0)git-gui $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(INSTALL_X0)git-gui--askpass $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
+	$(QUIET)$(INSTALL_X0)git-gui--askyesno $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(INSTALL_L0)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L1)'$(DESTDIR_SQ)$(gitexecdir_SQ)/git-gui' $(INSTALL_L2)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L3) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(INSTALL_R0)git-gui.tcl $(INSTALL_R1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
@@ -241,6 +242,7 @@ uninstall:
 	$(QUIET)$(CLEAN_DST) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui $(REMOVE_F1)
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui--askpass $(REMOVE_F1)
+	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui--askyesno $(REMOVE_F1)
 	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/$p $(REMOVE_F1) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui.tcl $(REMOVE_F1)
diff --git a/git-gui--askyesno b/git-gui--askyesno
new file mode 100755
index 0000000..9f084ce
--- /dev/null
+++ b/git-gui--askyesno
@@ -0,0 +1,36 @@
+#!/bin/sh
+# Tcl ignores the next line -*- tcl -*- \
+exec wish "$0" -- "$@"
+
+# This is an implementation of a simple yes no dialog
+# which is injected into the git commandline by git gui
+# in case a yesno question needs to be answered.
+
+set title "Question?"
+if {$argc < 1} {
+	puts stderr "Usage: $argv0 <question>"
+	exit 1
+} else {
+	if {$argc > 2 && [lindex $argv 0] == "--title"} {
+		set title [lindex $argv 1]
+		set argv [lreplace $argv 0 1]
+	}
+	set prompt [join $argv " "]
+}
+
+set dicon {question}
+if {$::tcl_platform(platform) eq {windows}} {
+	set icopath [file dirname [file normalize $argv0]]
+	if {[file tail $icopath] eq {git-core}} {
+		set icopath [file dirname $icopath]
+	}
+	set icopath [file dirname $icopath]
+	set icopath [file join $icopath share git git-for-windows.ico]
+	if {[file exists $icopath]} {
+		set dicon $iconpath
+	}
+}
+
+wm withdraw .
+set ans [tk_dialog .d $title $prompt $dicon 1 "Yes" "No"]
+exit $ans
diff --git a/git-gui.sh b/git-gui.sh
index d4b1d95..66f148e 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -1108,6 +1108,12 @@ citool {
 if {![info exists env(SSH_ASKPASS)]} {
 	set env(SSH_ASKPASS) [file join [git --exec-path] git-gui--askpass]
 }
+if {![info exists env(GIT_ASKPASS)]} {
+	set env(GIT_ASKPASS) [gitexec git-gui--askpass]
+}
+if {![info exists env(GIT_ASK_YESNO)]} {
+	set env(GIT_ASK_YESNO) [gitexec git-gui--askyesno]
+}
 
 ######################################################################
 ##