diff --git a/src/Makefile.am b/src/Makefile.am
index 9cdfc897d..375ff9147 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -275,7 +275,7 @@ Shell_0_1_gir_CFLAGS = $(libgnome_shell_la_CPPFLAGS) -I $(srcdir)
 Shell_0_1_gir_LIBS = libgnome-shell.la
 Shell_0_1_gir_FILES = $(libgnome_shell_la_gir_sources)
 Shell_0_1_gir_SCANNERFLAGS = --include-uninstalled=$(builddir)/St-1.0.gir \
-	--add-include-path=$(MUTTER_GIR_DIR) -L $(BLUETOOTH_DIR)
+	--add-include-path=$(MUTTER_GIR_DIR) $(if $(BLUETOOTH_DIR),-L $(BLUETOOTH_DIR),)
 INTROSPECTION_GIRS += Shell-0.1.gir
 CLEANFILES += Shell-0.1.gir