diff --git a/.travis.yml b/.travis.yml
index 4ca18a93ea86e..130a7f1fa6d61 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -51,8 +51,9 @@ matrix:
     # We don't want to run these always because they go towards
     # the build limit within the Travis rust-lang account.
     # The jobs are approximately sorted by execution time
-    - env: INTEGRATION=rust-lang/cargo
-      if: repo =~ /^rust-lang\/rust-clippy$/ AND branch IN (auto, try)
+    # disabled cargo integration test due to https://github.com/rust-lang/rust-clippy/issues/4121
+    #- env: INTEGRATION=rust-lang/cargo
+    #  if: repo =~ /^rust-lang\/rust-clippy$/ AND branch IN (auto, try)
     - env: INTEGRATION=rust-lang-nursery/chalk
       if: repo =~ /^rust-lang\/rust-clippy$/ AND branch IN (auto, try)
     - env: INTEGRATION=rust-lang/rls
diff --git a/clippy_lints/src/enum_variants.rs b/clippy_lints/src/enum_variants.rs
index 4479349aaf4a0..782d80a7b643b 100644
--- a/clippy_lints/src/enum_variants.rs
+++ b/clippy_lints/src/enum_variants.rs
@@ -248,7 +248,7 @@ impl EarlyLintPass for EnumVariantNames {
             if let Some(&(ref mod_name, ref mod_camel)) = self.modules.last() {
                 // constants don't have surrounding modules
                 if !mod_camel.is_empty() {
-                    if *mod_name == item_name {
+                    if mod_name.as_symbol() == item.ident.name {
                         if let ItemKind::Mod(..) = item.node {
                             span_lint(
                                 cx,
diff --git a/clippy_lints/src/format.rs b/clippy_lints/src/format.rs
index 25a5e2eca4386..2eaa1ac456474 100644
--- a/clippy_lints/src/format.rs
+++ b/clippy_lints/src/format.rs
@@ -61,7 +61,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UselessFormat {
                         then {
                             let (message, sugg) = if_chain! {
                                 if let ExprKind::MethodCall(ref path, _, _) = format_arg.node;
-                                if path.ident.as_interned_str() == "to_string";
+                                if path.ident.as_interned_str().as_symbol() == sym!(to_string);
                                 then {
                                     ("`to_string()` is enough",
                                     snippet(cx, format_arg.span, "<arg>").to_string())
diff --git a/clippy_lints/src/utils/higher.rs b/clippy_lints/src/utils/higher.rs
index 6ba2f91eb03af..dda05d3fbc524 100644
--- a/clippy_lints/src/utils/higher.rs
+++ b/clippy_lints/src/utils/higher.rs
@@ -63,10 +63,10 @@ pub fn range<'a, 'b, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'b hir::Expr) -> O
     if def_path.data.len() != 3 {
         return None;
     }
-    if def_path.data.get(0)?.data.as_interned_str() != "ops" {
+    if def_path.data.get(0)?.data.as_interned_str().as_symbol() != sym!(ops) {
         return None;
     }
-    if def_path.data.get(1)?.data.as_interned_str() != "range" {
+    if def_path.data.get(1)?.data.as_interned_str().as_symbol() != sym!(range) {
         return None;
     }
     let type_name = def_path.data.get(2)?.data.as_interned_str();