Support rustc 1.31 import restriction
diff --git a/src/lib.rs b/src/lib.rs
index 3c6c376..7fdb2cc 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -107,7 +107,7 @@
 mod fallback;
 
 #[cfg(not(wrap_proc_macro))]
-use fallback as imp;
+use crate::fallback as imp;
 #[path = "wrapper.rs"]
 #[cfg(wrap_proc_macro)]
 mod imp;