Index: RepositoryExternal.mk
--- RepositoryExternal.mk.orig
+++ RepositoryExternal.mk
@@ -647,6 +647,7 @@ endef
 gb_ExternalProject__use_boost_system :=
 
 define gb_LinkTarget__use_boost_headers
+$(call gb_LinkTarget_add_defs,$(1),-I$(call gb_UnpackedTarball_get_dir,boost))
 $(call gb_LinkTarget_set_include,$(1),\
 	$$(INCLUDE) \
 	$(BOOST_CPPFLAGS) \
@@ -3696,6 +3697,10 @@ gb_LinkTarget__use_libgpg-error :=
 endif # ENABLE_GPGMEPP
 
 define gb_LinkTarget__use_dconf
+$(call gb_LinkTarget_set_include,$(1),\
+	$$(INCLUDE) \
+	$(DCONF_CFLAGS) \
+)
 $(call gb_LinkTarget_set_include,$(1),\
 		$$(INCLUDE) \
 		$(DCONF_CFLAGS) \