diff --git a/src/mut_mut.rs b/src/mut_mut.rs
index bf8155b5c3c..b1e21def574 100644
--- a/src/mut_mut.rs
+++ b/src/mut_mut.rs
@@ -2,6 +2,7 @@ use syntax::ptr::P;
 use syntax::ast::*;
 use rustc::lint::{Context, LintPass, LintArray, Lint};
 use rustc::middle::ty::{expr_ty, sty, ty_ptr, ty_rptr, mt};
+use syntax::codemap::ExpnInfo;
 
 declare_lint!(pub MUT_MUT, Warn,
               "Warn on usage of double-mut refs, e.g. '&mut &mut ...'");
@@ -15,27 +16,8 @@ impl LintPass for MutMut {
 	}
 	
 	fn check_expr(&mut self, cx: &Context, expr: &Expr) {
-		
-		fn unwrap_addr(expr : &Expr) -> Option<&Expr> {
-			match expr.node {
-				ExprAddrOf(MutMutable, ref e) => Option::Some(e),
-				_ => Option::None
-			}
-		}
-		
-		unwrap_addr(expr).map_or((), |e| {
-			unwrap_addr(e).map(|_| {
-				cx.span_lint(MUT_MUT, expr.span, 
-					"Generally you want to avoid &mut &mut _ if possible.")
-			}).unwrap_or_else(|| {
-				if let ty_rptr(_, mt{ty: _, mutbl: MutMutable}) = 
-						expr_ty(cx.tcx, e).sty {
-					cx.span_lint(MUT_MUT, expr.span,
-						"This expression mutably borrows a mutable reference. \
-						Consider reborrowing")
-				}
-			})
-		})
+		cx.sess().codemap().with_expn_info(expr.span.expn_id, 
+			|info| check_expr_expd(cx, expr, info))
 	}
 	
 	fn check_ty(&mut self, cx: &Context, ty: &Ty) {
@@ -44,6 +26,35 @@ impl LintPass for MutMut {
 	}
 }
 
+fn check_expr_expd(cx: &Context, expr: &Expr, info: Option<&ExpnInfo>) {
+	if in_external_macro(info) { return; }
+
+	fn unwrap_addr(expr : &Expr) -> Option<&Expr> {
+		match expr.node {
+			ExprAddrOf(MutMutable, ref e) => Option::Some(e),
+			_ => Option::None
+		}
+	}
+	
+	unwrap_addr(expr).map_or((), |e| {
+		unwrap_addr(e).map(|_| {
+			cx.span_lint(MUT_MUT, expr.span, 
+				"Generally you want to avoid &mut &mut _ if possible.")
+		}).unwrap_or_else(|| {
+			if let ty_rptr(_, mt{ty: _, mutbl: MutMutable}) = 
+					expr_ty(cx.tcx, e).sty {
+				cx.span_lint(MUT_MUT, expr.span,
+					"This expression mutably borrows a mutable reference. \
+					Consider reborrowing")
+			}
+		})
+	})
+}
+
+fn in_external_macro(info: Option<&ExpnInfo>) -> bool {
+	info.map_or(false, |i| i.callee.span.is_some())
+}
+
 fn unwrap_mut(ty : &Ty) -> Option<&Ty> {
 	match ty.node {
 		TyPtr(MutTy{ ty: ref pty, mutbl: MutMutable }) => Option::Some(pty),