diff --git a/clippy_lints/src/macro_use.rs b/clippy_lints/src/macro_use.rs
index 7e3ce07254f7..b845b20d2c01 100644
--- a/clippy_lints/src/macro_use.rs
+++ b/clippy_lints/src/macro_use.rs
@@ -164,34 +164,37 @@ impl<'l, 'txc> LateLintPass<'l, 'txc> for MacroUseImports {
                 let seg = import.split("::").collect::<Vec<_>>();
 
                 match seg.as_slice() {
-                    [] => unreachable!("this should never be empty"),
-                    [_] => unreachable!("path must have two segments ?"),
+                    // an empty path is impossible
+                    // a path should always consist of 2 or more segments
+                    [] | [_] => return,
                     [root, item] => {
                         if !check_dup.contains(&(*item).to_string()) {
-                            used.entry((root.to_string(), span))
-                                .or_insert_with(|| vec![])
-                                .push(item.to_string());
-                            check_dup.push(item.to_string());
+                            used.entry(((*root).to_string(), span))
+                                .or_insert_with(Vec::new)
+                                .push((*item).to_string());
+                            check_dup.push((*item).to_string());
                         }
                     },
                     [root, rest @ ..] => {
                         if rest.iter().all(|item| !check_dup.contains(&(*item).to_string())) {
                             let filtered = rest
                                 .iter()
-                                .filter_map(|item| if check_dup.contains(&(*item).to_string()) {
-                                    None
-                                } else {
-                                    Some(item.to_string())
+                                .filter_map(|item| {
+                                    if check_dup.contains(&(*item).to_string()) {
+                                        None
+                                    } else {
+                                        Some((*item).to_string())
+                                    }
                                 })
                                 .collect::<Vec<_>>();
                             used.entry(((*root).to_string(), span))
-                                .or_insert_with(|| vec![])
+                                .or_insert_with(Vec::new)
                                 .push(filtered.join("::"));
                             check_dup.extend(filtered);
                         } else {
                             let rest = rest.to_vec();
-                            used.entry((root.to_string(), span))
-                                .or_insert_with(|| vec![])
+                            used.entry(((*root).to_string(), span))
+                                .or_insert_with(Vec::new)
                                 .push(rest.join("::"));
                             check_dup.extend(rest.iter().map(ToString::to_string));
                         }
diff --git a/tests/ui/macro_use_imports.fixed b/tests/ui/macro_use_imports.fixed
index 8034c56b59ad..3178729f68c0 100644
--- a/tests/ui/macro_use_imports.fixed
+++ b/tests/ui/macro_use_imports.fixed
@@ -3,6 +3,7 @@
 // aux-build:macro_use_helper.rs
 // run-rustfix
 
+#![allow(unused_imports, unreachable_code, unused_variables, dead_code)]
 #![allow(clippy::single_component_path_imports)]
 #![warn(clippy::macro_use_imports)]
 
diff --git a/tests/ui/macro_use_imports.rs b/tests/ui/macro_use_imports.rs
index 7d415222d64f..932bc0630d8d 100644
--- a/tests/ui/macro_use_imports.rs
+++ b/tests/ui/macro_use_imports.rs
@@ -3,6 +3,7 @@
 // aux-build:macro_use_helper.rs
 // run-rustfix
 
+#![allow(unused_imports, unreachable_code, unused_variables, dead_code)]
 #![allow(clippy::single_component_path_imports)]
 #![warn(clippy::macro_use_imports)]
 
diff --git a/tests/ui/macro_use_imports.stderr b/tests/ui/macro_use_imports.stderr
index 6feda8a52226..3a1d3122c242 100644
--- a/tests/ui/macro_use_imports.stderr
+++ b/tests/ui/macro_use_imports.stderr
@@ -1,25 +1,25 @@
 error: `macro_use` attributes are no longer needed in the Rust 2018 edition
-  --> $DIR/macro_use_imports.rs:18:5
+  --> $DIR/macro_use_imports.rs:17:5
    |
 LL |     #[macro_use]
-   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mini_mac::ClippyMiniMacroTest;`
+   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::{pub_macro, inner_mod_macro, function_macro, ty_macro, pub_in_private_macro};`
    |
    = note: `-D clippy::macro-use-imports` implied by `-D warnings`
 
 error: `macro_use` attributes are no longer needed in the Rust 2018 edition
-  --> $DIR/macro_use_imports.rs:20:5
+  --> $DIR/macro_use_imports.rs:19:5
    |
 LL |     #[macro_use]
-   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::{inner::foofoo, inner::try_err};`
+   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mini_mac::ClippyMiniMacroTest;`
 
 error: `macro_use` attributes are no longer needed in the Rust 2018 edition
-  --> $DIR/macro_use_imports.rs:16:5
+  --> $DIR/macro_use_imports.rs:21:5
    |
 LL |     #[macro_use]
-   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::{pub_macro, inner_mod_macro, function_macro, ty_macro, pub_in_private_macro};`
+   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::{inner::foofoo, inner::try_err};`
 
 error: `macro_use` attributes are no longer needed in the Rust 2018 edition
-  --> $DIR/macro_use_imports.rs:22:5
+  --> $DIR/macro_use_imports.rs:23:5
    |
 LL |     #[macro_use]
    |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::inner::nested::string_add;`