diff --git a/src/librustc/ich/impls_const_math.rs b/src/librustc/ich/impls_const_math.rs
index 387a6d5f35c..494fa49b53d 100644
--- a/src/librustc/ich/impls_const_math.rs
+++ b/src/librustc/ich/impls_const_math.rs
@@ -17,7 +17,6 @@ impl_stable_hash_for!(struct ::rustc_const_math::ConstFloat {
 });
 
 impl_stable_hash_for!(enum ::rustc_const_math::ConstMathErr {
-    UnequalTypes(op),
     Overflow(op),
     DivisionByZero,
     RemainderByZero,
diff --git a/src/librustc_const_math/err.rs b/src/librustc_const_math/err.rs
index 5d442ee7b97..94a51c23a5e 100644
--- a/src/librustc_const_math/err.rs
+++ b/src/librustc_const_math/err.rs
@@ -10,7 +10,6 @@
 
 #[derive(Debug, PartialEq, Eq, Clone, RustcEncodable, RustcDecodable)]
 pub enum ConstMathErr {
-    UnequalTypes(Op),
     Overflow(Op),
     DivisionByZero,
     RemainderByZero,
@@ -36,17 +35,6 @@ impl ConstMathErr {
     pub fn description(&self) -> &'static str {
         use self::Op::*;
         match *self {
-            UnequalTypes(Add) => "tried to add two values of different types",
-            UnequalTypes(Sub) => "tried to subtract two values of different types",
-            UnequalTypes(Mul) => "tried to multiply two values of different types",
-            UnequalTypes(Div) => "tried to divide two values of different types",
-            UnequalTypes(Rem) => {
-                "tried to calculate the remainder of two values of different types"
-            },
-            UnequalTypes(BitAnd) => "tried to bitand two values of different types",
-            UnequalTypes(BitOr) => "tried to bitor two values of different types",
-            UnequalTypes(BitXor) => "tried to xor two values of different types",
-            UnequalTypes(_) => unreachable!(),
             Overflow(Add) => "attempt to add with overflow",
             Overflow(Sub) => "attempt to subtract with overflow",
             Overflow(Mul) => "attempt to multiply with overflow",
diff --git a/src/librustc_const_math/float.rs b/src/librustc_const_math/float.rs
index 61e9b34f06a..35cfe466c8a 100644
--- a/src/librustc_const_math/float.rs
+++ b/src/librustc_const_math/float.rs
@@ -16,8 +16,6 @@ use syntax::ast;
 use rustc_apfloat::{Float, FloatConvert, Status};
 use rustc_apfloat::ieee::{Single, Double};
 
-use super::err::*;
-
 // Note that equality for `ConstFloat` means that the it is the same
 // constant, not that the rust values are equal. In particular, `NaN
 // == NaN` (at least if it's the same NaN; distinct encodings for NaN
@@ -172,8 +170,8 @@ impl ::std::fmt::Debug for ConstFloat {
 macro_rules! derive_binop {
     ($op:ident, $func:ident) => {
         impl ::std::ops::$op for ConstFloat {
-            type Output = Result<Self, ConstMathErr>;
-            fn $func(self, rhs: Self) -> Result<Self, ConstMathErr> {
+            type Output = Option<Self>;
+            fn $func(self, rhs: Self) -> Option<Self> {
                 let bits = match (self.ty, rhs.ty) {
                     (ast::FloatTy::F32, ast::FloatTy::F32) =>{
                         let a = Single::from_bits(self.bits);
@@ -185,9 +183,9 @@ macro_rules! derive_binop {
                         let b = Double::from_bits(rhs.bits);
                         a.$func(b).value.to_bits()
                     }
-                    _ => return Err(UnequalTypes(Op::$op)),
+                    _ => return None,
                 };
-                Ok(ConstFloat { bits, ty: self.ty })
+                Some(ConstFloat { bits, ty: self.ty })
             }
         }
     }