diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index a0e7fe17e8ea0..f4a7497dbe020 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -38,7 +38,7 @@ pub struct GroupLabel(pub String);
 impl AssistLabel {
     pub(crate) fn new(label: String, id: AssistId) -> AssistLabel {
         // FIXME: make fields private, so that this invariant can't be broken
-        assert!(label.chars().next().unwrap().is_uppercase());
+        assert!(label.starts_with(|c: char| c.is_uppercase()));
         AssistLabel { label, id }
     }
 }
diff --git a/crates/ra_ide/src/completion/presentation.rs b/crates/ra_ide/src/completion/presentation.rs
index 1a3bcffaeb20b..a524987fd5d00 100644
--- a/crates/ra_ide/src/completion/presentation.rs
+++ b/crates/ra_ide/src/completion/presentation.rs
@@ -135,11 +135,7 @@ impl Completions {
             let (before, after) = (&docs[..idx], &docs[idx + s.len()..]);
             // Ensure to match the full word
             if after.starts_with('!')
-                && before
-                    .chars()
-                    .rev()
-                    .next()
-                    .map_or(true, |c| c != '_' && !c.is_ascii_alphanumeric())
+                && !before.ends_with(|c: char| c == '_' || c.is_ascii_alphanumeric())
             {
                 // It may have spaces before the braces like `foo! {}`
                 match after[1..].chars().find(|&c| !c.is_whitespace()) {
diff --git a/crates/ra_mbe/src/subtree_source.rs b/crates/ra_mbe/src/subtree_source.rs
index eb8b79e9a8019..dacca82794f74 100644
--- a/crates/ra_mbe/src/subtree_source.rs
+++ b/crates/ra_mbe/src/subtree_source.rs
@@ -141,7 +141,7 @@ fn convert_literal(l: &tt::Literal) -> TtToken {
 }
 
 fn convert_ident(ident: &tt::Ident) -> TtToken {
-    let kind = if let Some('\'') = ident.text.chars().next() {
+    let kind = if ident.text.starts_with('\'') {
         LIFETIME
     } else {
         SyntaxKind::from_keyword(ident.text.as_str()).unwrap_or(IDENT)