diff --git a/Makefile b/Makefile
index cde8b2e..4f00bdd 100644
--- a/Makefile
+++ b/Makefile
@@ -177,7 +177,8 @@
 	echo then >>$@+ && \
 	echo '	'echo \'git-gui version '$(GITGUI_VERSION)'\' >>$@+ && \
 	echo else >>$@+ && \
-	echo '	'exec \''$(libdir_SQ)/Git Gui.app/Contents/MacOS/$(subst \,,$(TKEXECUTABLE))'\' \
+	echo '	libdir="$${GIT_GUI_LIB_DIR:-$(libdir_SQ)}"' >>$@+ && \
+	echo '	'exec \"'$$libdir/Git Gui.app/Contents/MacOS/$(subst \,,$(TKEXECUTABLE))'\" \
 		'"$$0" "$$@"' >>$@+ && \
 	echo fi >>$@+ && \
 	chmod +x $@+ && \
diff --git a/git-gui.sh b/git-gui.sh
index b186329..6cbb36e 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -49,7 +49,11 @@
 ##
 ## locate our library
 
-set oguilib {@@GITGUI_LIBDIR@@}
+if { [info exists ::env(GIT_GUI_LIB_DIR) ] } {
+	set oguilib $::env(GIT_GUI_LIB_DIR)
+} else {
+	set oguilib {@@GITGUI_LIBDIR@@}
+}
 set oguirel {@@GITGUI_RELATIVE@@}
 if {$oguirel eq {1}} {
 	set oguilib [file dirname [file normalize $argv0]]
diff --git a/macosx/AppMain.tcl b/macosx/AppMain.tcl
index 738bdd0..b6c6dc3 100644
--- a/macosx/AppMain.tcl
+++ b/macosx/AppMain.tcl
@@ -1,5 +1,10 @@
 set gitexecdir {@@gitexecdir@@}
-set gitguilib  {@@GITGUI_LIBDIR@@}
+if { [info exists ::env(GIT_GUI_LIB_DIR) ] } {
+	set gitguilib $::env(GIT_GUI_LIB_DIR)
+} else {
+	set gitguilib {@@GITGUI_LIBDIR@@}
+}
+
 set env(PATH) "$gitexecdir:$env(PATH)"
 
 if {[string first -psn [lindex $argv 0]] == 0} {