diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index 439cc3a4b844..b97920dd18b7 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -153,6 +153,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
         };
 
         let mut fn_warned = false;
+        let mut op_warned = false;
         if cx.tcx.sess.features.borrow().fn_must_use {
             let maybe_def = match expr.node {
                 hir::ExprCall(ref callee, _) => {
@@ -172,9 +173,24 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
                 let def_id = def.def_id();
                 fn_warned = check_must_use(cx, def_id, s.span, "return value of ");
             }
+
+            if let hir::ExprBinary(bin_op, ..) = expr.node {
+                match bin_op.node {
+                    // Hardcoding the comparison operators here seemed more
+                    // expedient than the refactoring that would be needed to
+                    // look up the `#[must_use]` attribute which does exist on
+                    // the comparison trait methods
+                    hir::BiEq | hir::BiLt | hir::BiLe | hir::BiNe | hir::BiGe | hir::BiGt => {
+                        let msg = "unused comparison which must be used";
+                        cx.span_lint(UNUSED_MUST_USE, expr.span, msg);
+                        op_warned = true;
+                    },
+                    _ => {},
+                }
+            }
         }
 
-        if !(ty_warned || fn_warned) {
+        if !(ty_warned || fn_warned || op_warned) {
             cx.span_lint(UNUSED_RESULTS, s.span, "unused result");
         }
 
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 1fef382c83a3..5c730aaa8d0f 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -380,7 +380,7 @@ declare_features! (
     // #[doc(masked)]
     (active, doc_masked, "1.21.0", None),
 
-    // allow `#[must_use]` on functions (RFC 1940)
+    // allow `#[must_use]` on functions and comparison operators (RFC 1940)
     (active, fn_must_use, "1.21.0", Some(43302)),
 
     // allow '|' at beginning of match arms (RFC 1925)
diff --git a/src/test/ui/rfc_1940-must_use_on_functions/fn_must_use.rs b/src/test/ui/rfc_1940-must_use_on_functions/fn_must_use.rs
index 7eb4c32972a2..821cd30c8df4 100644
--- a/src/test/ui/rfc_1940-must_use_on_functions/fn_must_use.rs
+++ b/src/test/ui/rfc_1940-must_use_on_functions/fn_must_use.rs
@@ -61,10 +61,9 @@ fn main() {
     m.need_to_use_this_method_value();
     m.is_even(); // trait method!
 
-    m.replace(3);
+    m.replace(3); // won't warn (annotation needs to be in trait definition)
 
-    2.eq(&3);
+    2.eq(&3); // comparison methods are `must_use`
 
-    // FIXME: operators should probably be `must_use` if underlying method is
-    2 == 3;
+    2 == 3; // lint includes comparison operators
 }
diff --git a/src/test/ui/rfc_1940-must_use_on_functions/fn_must_use.stderr b/src/test/ui/rfc_1940-must_use_on_functions/fn_must_use.stderr
index 69755c89b484..7fc0a4ce1edc 100644
--- a/src/test/ui/rfc_1940-must_use_on_functions/fn_must_use.stderr
+++ b/src/test/ui/rfc_1940-must_use_on_functions/fn_must_use.stderr
@@ -25,6 +25,12 @@ warning: unused return value of `EvenNature::is_even` which must be used: no sid
 warning: unused return value of `std::cmp::PartialEq::eq` which must be used
   --> $DIR/fn_must_use.rs:66:5
    |
-66 |     2.eq(&3);
+66 |     2.eq(&3); // comparison methods are `must_use`
    |     ^^^^^^^^^
 
+warning: unused comparison which must be used
+  --> $DIR/fn_must_use.rs:68:5
+   |
+68 |     2 == 3; // lint includes comparison operators
+   |     ^^^^^^
+