diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index fc7a3d8e0213..e59cc8912d83 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -1111,6 +1111,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&methods::FILTER_MAP),
         LintId::of(&methods::FILTER_MAP_NEXT),
         LintId::of(&methods::FIND_MAP),
+        LintId::of(&methods::INEFFICIENT_TO_STRING),
         LintId::of(&methods::MAP_FLATTEN),
         LintId::of(&methods::OPTION_MAP_UNWRAP_OR),
         LintId::of(&methods::OPTION_MAP_UNWRAP_OR_ELSE),
@@ -1267,7 +1268,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&methods::EXPECT_FUN_CALL),
         LintId::of(&methods::FILTER_NEXT),
         LintId::of(&methods::FLAT_MAP_IDENTITY),
-        LintId::of(&methods::INEFFICIENT_TO_STRING),
         LintId::of(&methods::INTO_ITER_ON_REF),
         LintId::of(&methods::ITERATOR_STEP_BY_ZERO),
         LintId::of(&methods::ITER_CLONED_COLLECT),
@@ -1657,7 +1657,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&loops::MANUAL_MEMCPY),
         LintId::of(&loops::NEEDLESS_COLLECT),
         LintId::of(&methods::EXPECT_FUN_CALL),
-        LintId::of(&methods::INEFFICIENT_TO_STRING),
         LintId::of(&methods::ITER_NTH),
         LintId::of(&methods::OR_FUN_CALL),
         LintId::of(&methods::SINGLE_CHAR_PATTERN),
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
index 31dbf6b2b385..e287d2ad484d 100644
--- a/clippy_lints/src/methods/mod.rs
+++ b/clippy_lints/src/methods/mod.rs
@@ -699,7 +699,7 @@
     /// ["foo", "bar"].iter().map(|&s| s.to_string());
     /// ```
     pub INEFFICIENT_TO_STRING,
-    perf,
+    pedantic,
     "using `to_string` on `&&T` where `T: ToString`"
 }
 
diff --git a/src/lintlist/mod.rs b/src/lintlist/mod.rs
index d7dab78fbe4f..c48afc823478 100644
--- a/src/lintlist/mod.rs
+++ b/src/lintlist/mod.rs
@@ -789,7 +789,7 @@
     },
     Lint {
         name: "inefficient_to_string",
-        group: "perf",
+        group: "pedantic",
         desc: "using `to_string` on `&&T` where `T: ToString`",
         deprecation: None,
         module: "methods",