diff --git a/src/libstd/mtypes.rs b/src/libstd/mtypes.rs
new file mode 100644
index 0000000000000..cddea420cc836
--- /dev/null
+++ b/src/libstd/mtypes.rs
@@ -0,0 +1,64 @@
+/*
+
+Module: mtypes
+
+Machine type equivalents of rust int, uint, float, and complex.
+
+Types useful for interop with C when writing bindings that exist
+for different types (float, f32, f64, ...; cf float.rs for an example)
+*/
+
+export m_int, m_uint, m_float;
+
+// PORT Change this when porting to a new architecture
+
+/*
+Type: m_int
+
+Machine type equivalent of an int
+*/
+#[cfg(target_arch="x86")]
+type m_int = i32;
+#[cfg(target_arch="x86_64")]
+type m_int = i64;
+
+// PORT Change this when porting to a new architecture
+
+/*
+Type: m_uint
+
+Machine type equivalent of a uint
+*/
+#[cfg(target_arch="x86")]
+type m_uint = u32;
+#[cfg(target_arch="x86_64")]
+type m_uint = u64;
+
+// PORT *must* match with "import m_float = fXX" in std::math per arch
+
+/*
+Type: m_float
+
+Machine type equivalent of a float
+*/
+type m_float = f64;
+
+// PORT  *must* match "import m_complex = ..." in std::complex per arch
+
+/*
+FIXME Type m_complex
+
+Machine type representing a complex value that uses floats for
+both the real and the imaginary part.
+*/
+// type m_complex = complex_c64::t;
+
+//
+// Local Variables:
+// mode: rust
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// End:
+//
diff --git a/src/test/compile-fail/non-triv-cast-be.rs b/src/test/compile-fail/non-triv-cast-be.rs
index 74a0e4da2880a..458013a912c9c 100644
--- a/src/test/compile-fail/non-triv-cast-be.rs
+++ b/src/test/compile-fail/non-triv-cast-be.rs
@@ -1,7 +1,5 @@
 // error-pattern: non-trivial cast of tail-call return value
-use std;
-
-import ctypes::*;
+import core::mtypes::*;
 
 fn foo_float() -> m_float { ret 0.0 as m_float; }
 fn bar_float() -> bool { be foo_float() as bool; }
diff --git a/src/test/run-pass/triv-cast-be.rs b/src/test/run-pass/triv-cast-be.rs
index 96ab736c5255a..0fbb1ad283009 100644
--- a/src/test/run-pass/triv-cast-be.rs
+++ b/src/test/run-pass/triv-cast-be.rs
@@ -1,6 +1,8 @@
-use std;
+import core::ctypes::*;
 
-import ctypes::*;
+import core::mtypes::m_float;
+import core::mtypes::m_int;
+import core::mtypes::m_uint;
 
 fn foo_float() -> m_float { ret 0.0 as m_float; }
 fn bar_float() -> float { be foo_float() as float; }
diff --git a/src/test/run-pass/triv-cast-const.rs b/src/test/run-pass/triv-cast-const.rs
index 5aae65ea384d1..0880fc82c48db 100644
--- a/src/test/run-pass/triv-cast-const.rs
+++ b/src/test/run-pass/triv-cast-const.rs
@@ -1,6 +1,4 @@
-use std;
-
-import ctypes::*;
+import core::mtypes::m_int;
 
 // This will be more interesting once there is support
 // for consts that refer to other consts, i.e. math_f64::consts::pi as m_float