diff --git a/src/librustc/middle/resolve_lifetime.rs b/src/librustc/middle/resolve_lifetime.rs
index e2b1b54cef39..f6c62d191fa6 100644
--- a/src/librustc/middle/resolve_lifetime.rs
+++ b/src/librustc/middle/resolve_lifetime.rs
@@ -2568,7 +2568,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
         let lifetimes: Vec<_> = params
             .iter()
             .filter_map(|param| match param.kind {
-                GenericParamKind::Lifetime { .. } => Some((param, param.name)),
+                GenericParamKind::Lifetime { .. } => Some((param, param.name.modern())),
                 _ => None,
             })
             .collect();
diff --git a/src/test/ui/hygiene/duplicate_lifetimes.rs b/src/test/ui/hygiene/duplicate_lifetimes.rs
new file mode 100644
index 000000000000..e7312b51dbcb
--- /dev/null
+++ b/src/test/ui/hygiene/duplicate_lifetimes.rs
@@ -0,0 +1,19 @@
+// Ensure that lifetime parameter names are modernized before we check for
+// duplicates.
+
+#![feature(decl_macro, rustc_attrs)]
+
+#[rustc_macro_transparency = "semitransparent"]
+macro m($a:lifetime) {
+    fn g<$a, 'a>() {} //~ ERROR lifetime name `'a` declared twice
+}
+
+#[rustc_macro_transparency = "transparent"]
+macro n($a:lifetime) {
+    fn h<$a, 'a>() {} //~ ERROR lifetime name `'a` declared twice
+}
+
+m!('a);
+n!('a);
+
+fn main() {}
diff --git a/src/test/ui/hygiene/duplicate_lifetimes.stderr b/src/test/ui/hygiene/duplicate_lifetimes.stderr
new file mode 100644
index 000000000000..7aaea6ff24e3
--- /dev/null
+++ b/src/test/ui/hygiene/duplicate_lifetimes.stderr
@@ -0,0 +1,27 @@
+error[E0263]: lifetime name `'a` declared twice in the same scope
+  --> $DIR/duplicate_lifetimes.rs:8:14
+   |
+LL |     fn g<$a, 'a>() {}
+   |              ^^ declared twice
+...
+LL | m!('a);
+   | -------
+   | |  |
+   | |  previous declaration here
+   | in this macro invocation
+
+error[E0263]: lifetime name `'a` declared twice in the same scope
+  --> $DIR/duplicate_lifetimes.rs:13:14
+   |
+LL |     fn h<$a, 'a>() {}
+   |              ^^ declared twice
+...
+LL | n!('a);
+   | -------
+   | |  |
+   | |  previous declaration here
+   | in this macro invocation
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0263`.