diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index a0e7fe17e8e..f4a7497dbe0 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 1a3bcffaeb2..a524987fd5d 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_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index 3f88bb26068..1de3cb5796c 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -743,4 +743,21 @@ fn func(foo: i32) { if true { <|>foo; }; }
             &["u32"],
         );
     }
+
+    #[test]
+    fn test_hover_non_ascii_space_doc() {
+        check_hover_result(
+            "
+            //- /lib.rs
+            ///　<- `\u{3000}` here
+            fn foo() {
+            }
+
+            fn bar() {
+                fo<|>o();
+            }
+            ",
+            &["fn foo()\n```\n\n<- `\u{3000}` here"],
+        );
+    }
 }
diff --git a/crates/ra_mbe/src/subtree_source.rs b/crates/ra_mbe/src/subtree_source.rs
index eb8b79e9a80..dacca82794f 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)
diff --git a/crates/ra_syntax/src/ast/traits.rs b/crates/ra_syntax/src/ast/traits.rs
index f99984fe0f6..f8cf1e3eb46 100644
--- a/crates/ra_syntax/src/ast/traits.rs
+++ b/crates/ra_syntax/src/ast/traits.rs
@@ -126,8 +126,8 @@ pub trait DocCommentsOwner: AstNode {
 
                 // Determine if the prefix or prefix + 1 char is stripped
                 let pos =
-                    if line.chars().nth(prefix_len).map(|c| c.is_whitespace()).unwrap_or(false) {
-                        prefix_len + 1
+                    if let Some(ws) = line.chars().nth(prefix_len).filter(|c| c.is_whitespace()) {
+                        prefix_len + ws.len_utf8()
                     } else {
                         prefix_len
                     };