diff -up firefox-56.0/layout/style/bindgen.toml.in.old firefox-56.0/layout/style/bindgen.toml.in
--- firefox-56.0/layout/style/bindgen.toml.in.old	2017-09-27 16:30:14.518213900 +0200
+++ firefox-56.0/layout/style/bindgen.toml.in	2017-09-27 16:30:38.089179153 +0200
@@ -1,4 +1,5 @@
 [build]
 args = [
+    "/usr/include",
     @BINDGEN_CFLAGS@
 ]