diff --git a/lib/rouge/lexers/rust.rb b/lib/rouge/lexers/rust.rb
index e8c524eaf2..9befeeb37e 100644
--- a/lib/rouge/lexers/rust.rb
+++ b/lib/rouge/lexers/rust.rb
@@ -166,8 +166,8 @@ def macro_closed?
 
         rule %r(
           ( 0b[10_]+
-          | 0x[0-9a-fA-F-]+
-          | [0-9]+
+          | 0x[0-9a-fA-F_]+
+          | [0-9_]+
           ) (u#{size}?|i#{size})?
         )x, Num::Integer
 
diff --git a/spec/visual/samples/rust b/spec/visual/samples/rust
index fa772608cf..072473e6ff 100644
--- a/spec/visual/samples/rust
+++ b/spec/visual/samples/rust
@@ -381,6 +381,11 @@ enum HTMLFragment {
     text(~str),
 }
 
+fn int_literals_delimiter() {
+    let billion = 1000_000_000;
+    let red_color = 0xff_60_60;
+}
+
 // Some hidden lines by starting with hash
 # extern crate core;
 # use core::str;