diff --git a/mxe.github.mk b/mxe.github.mk
index 1c7aeb57..61e70f47 100644
--- a/mxe.github.mk
+++ b/mxe.github.mk
@@ -102,7 +102,7 @@ define MXE_SETUP_GITHUB
     $(PKG)_FILE        := $(or $($(PKG)_FILE),$(PKG)-$$(filter-out $$(PKG)-,$$($$(PKG)_TAG_PREFIX))$($(PKG)_VERSION)$$($$(PKG)_TAG_SUFFIX).tar.gz)
     $(if $(and $(GH_BRANCH),$(GH_TAG_VARS)),\
         $(error $(newline) $(PKG) specifies both branch and tag variables $(newline)))
-    $(if $(filter-out $(GH_APIS),$(GH_API)),\
+    $(if $(filter-out $(GH_APIS),$(GH_API))$(filter x,x$(GH_API)),\
         $(error $(newline) $(PKG) has unknown API $($(PKG)_GH_CONF) $(newline)))
     $(if $(GH_BRANCH),$(value MXE_SETUP_GITHUB_BRANCH),$(value MXE_SETUP_GITHUB_$(call uc,$(GH_API))))
 endef