diff --git a/src/rebar_port_compiler.erl b/src/rebar_port_compiler.erl
index fec8e04..35adc3c 100644
--- a/src/rebar_port_compiler.erl
+++ b/src/rebar_port_compiler.erl
@@ -565,10 +565,10 @@ default_env() ->
      {"EXE_CFLAGS" , "-g -Wall -fPIC $ERL_CFLAGS"},
      {"EXE_LDFLAGS", "$ERL_LDFLAGS"},
 
-     {"ERL_CFLAGS", lists:concat([" -I", erl_interface_dir(include),
-                                  " -I", filename:join(erts_dir(), "include"),
-                                  " "])},
-     {"ERL_EI_LIBDIR", erl_interface_dir(lib)},
+     {"ERL_CFLAGS", lists:concat([" -I\"", erl_interface_dir(include),
+                                  "\" -I\"", filename:join(erts_dir(), "include"),
+                                  "\" "])},
+     {"ERL_EI_LIBDIR", lists:concat(["\"", erl_interface_dir(lib), "\""])},
      {"ERL_LDFLAGS"  , " -L$ERL_EI_LIBDIR -lerl_interface -lei"},
      {"ERLANG_ARCH"  , rebar_utils:wordsize()},
      {"ERLANG_TARGET", rebar_utils:get_arch()},