diff --git a/.gitignore b/.gitignore
index 5130b4f..38a41eb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,4 +5,5 @@ GIT-GUI-BUILD-OPTIONS
 GIT-VERSION-FILE
 git-gui
 git-gui--askpass
+git-gui--askyesno
 lib/tclIndex
diff --git a/GIT-VERSION-GEN b/GIT-VERSION-GEN
index c2767b4..2f729de 100755
--- a/GIT-VERSION-GEN
+++ b/GIT-VERSION-GEN
@@ -5,19 +5,27 @@ DEF_VER=0.21.GITGUI
 LF='
 '
 
-if test "$#" -ne 2
+if test "$#" -lt 2
 then
-	echo >&2 "usage: $0 <SOURCE_DIR> <OUTPUT>"
+	echo >&2 "usage: $0 <SOURCE_DIR> <OUTPUT> [<PARENT_PROJECT_DIR>]"
 	exit 1
 fi
 
 SOURCE_DIR="$1"
 OUTPUT="$2"
+PARENT_PROJECT_DIR="$3"
 
 # Protect us from reading Git version information outside of the Git directory
 # in case it is not a repository itself, but embedded in an unrelated
-# repository.
-GIT_CEILING_DIRECTORIES="$SOURCE_DIR/.."
+# repository. The PARENT_PROJECT_DIR variable can be used to override this, for
+# example when git-gui is included as a subproject.
+if test -n "$PARENT_PROJECT_DIR"
+then
+	GIT_CEILING_DIRECTORIES="$PARENT_PROJECT_DIR/.."
+else
+	GIT_CEILING_DIRECTORIES="$SOURCE_DIR/.."
+fi
+
 export GIT_CEILING_DIRECTORIES
 
 tree_search ()
diff --git a/Makefile b/Makefile
index 69b0b84..ca01068 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@ all::
 #
 
 GIT-VERSION-FILE: FORCE
-	@$(SHELL_PATH) ./GIT-VERSION-GEN . $@
+	@$(SHELL_PATH) ./GIT-VERSION-GEN . $@ "$(PARENT_PROJECT_DIR)"
 
 uname_S := $(shell sh -c 'uname -s 2>/dev/null || echo not')
 uname_R := $(shell sh -c 'uname -r 2>/dev/null || echo not')
@@ -177,10 +177,13 @@ GIT-GUI-BUILD-OPTIONS: FORCE
 git-gui--askpass: git-gui--askpass.sh GIT-GUI-BUILD-OPTIONS generate-script.sh
 	$(QUIET_GEN)$(SHELL_PATH) generate-script.sh $@ $< ./GIT-GUI-BUILD-OPTIONS
 
+git-gui--askyesno: git-gui--askyesno.sh GIT-GUI-BUILD-OPTIONS generate-script.sh
+	$(QUIET_GEN)$(SHELL_PATH) generate-script.sh $@ $< ./GIT-GUI-BUILD-OPTIONS
+
 ifdef GITGUI_WINDOWS_WRAPPER
 all:: git-gui
 endif
-all:: $(GITGUI_MAIN) git-gui--askpass lib/tclIndex $(ALL_MSGFILES)
+all:: $(GITGUI_MAIN) git-gui--askpass git-gui--askyesno lib/tclIndex $(ALL_MSGFILES)
 
 install: all
 	$(QUIET)$(INSTALL_D0)'$(DESTDIR_SQ)$(gitexecdir_SQ)' $(INSTALL_D1)
@@ -221,7 +224,7 @@ dist-version: GIT-VERSION-FILE
 	@sed 's|^GITGUI_VERSION=||' <GIT-VERSION-FILE  >$(TARDIR)/version
 
 clean::
-	$(RM_RF) $(GITGUI_MAIN) git-gui--askpass lib/tclIndex po/*.msg $(PO_TEMPLATE)
+	$(RM_RF) $(GITGUI_MAIN) git-gui--askpass git-gui--askyesno lib/tclIndex po/*.msg $(PO_TEMPLATE)
 	$(RM_RF) GIT-VERSION-FILE GIT-GUI-BUILD-OPTIONS
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(RM_RF) git-gui
diff --git a/git-gui--askyesno b/git-gui--askyesno.sh
similarity index 100%
rename from git-gui--askyesno
rename to git-gui--askyesno.sh
diff --git a/meson.build b/meson.build
index 320ba09..a8119aa 100644
--- a/meson.build
+++ b/meson.build
@@ -4,7 +4,7 @@ project('git-gui',
 
 fs = import('fs')
 
-shell = find_program('sh')
+shell = find_program('/bin/sh', 'sh')
 tclsh = find_program('tclsh')
 wish = find_program('wish')
 
@@ -34,6 +34,7 @@ version_file = custom_target(
     '@INPUT@',
     meson.current_source_dir(),
     '@OUTPUT@',
+    get_option('parent_project_dir'),
   ],
   build_always_stale: true,
 )
@@ -53,19 +54,21 @@ if target_machine.system() == 'windows'
   )
 endif
 
-custom_target(
-  output: 'git-gui--askpass',
-  input: 'git-gui--askpass.sh',
-  command: [
-    shell,
-    meson.current_source_dir() / 'generate-script.sh',
-    '@OUTPUT@',
-    '@INPUT@',
-    meson.current_build_dir() / 'GIT-GUI-BUILD-OPTIONS',
-  ],
-  install: true,
-  install_dir: get_option('libexecdir') / 'git-core',
-)
+foreach script : [ 'git-gui--askpass', 'git-gui--askyesno' ]
+  custom_target(
+    output: script,
+    input: script + '.sh',
+    command: [
+      shell,
+      meson.current_source_dir() / 'generate-script.sh',
+      '@OUTPUT@',
+      '@INPUT@',
+      meson.current_build_dir() / 'GIT-GUI-BUILD-OPTIONS',
+    ],
+    install: true,
+    install_dir: get_option('libexecdir') / 'git-core',
+  )
+endforeach
 
 custom_target(
   input: 'git-gui.sh',
diff --git a/meson_options.txt b/meson_options.txt
new file mode 100644
index 0000000..7591a34
--- /dev/null
+++ b/meson_options.txt
@@ -0,0 +1,2 @@
+option('parent_project_dir', type: 'string', value: '',
+  description: 'The directory of the parent project. This is used so that the version can be determined even in case git-gui is included as a subtree.')