diff --git a/src/libcore/core.rc b/src/libcore/core.rc
index e91c2a34ea0..6315d32b6d4 100644
--- a/src/libcore/core.rc
+++ b/src/libcore/core.rc
@@ -44,7 +44,6 @@ mod result;
 // Runtime and language-primitive support
 
 mod ctypes;
-mod mtypes;
 mod cmath;
 mod sys;
 mod unsafe;