diff --git a/compiler/rustc_macros/src/diagnostics/error.rs b/compiler/rustc_macros/src/diagnostics/error.rs
index 0b1ededa77510..4612f54e4b176 100644
--- a/compiler/rustc_macros/src/diagnostics/error.rs
+++ b/compiler/rustc_macros/src/diagnostics/error.rs
@@ -84,7 +84,7 @@ pub(crate) fn invalid_attr(attr: &Attribute, meta: &Meta) -> Diagnostic {
     }
 }
 
-/// Emit a error diagnostic for an invalid attribute (optionally performing additional decoration
+/// Emit an error diagnostic for an invalid attribute (optionally performing additional decoration
 /// using the `FnOnce` passed in `diag`) and return `Err(ErrorHandled)`.
 ///
 /// For methods that return a `Result<_, DiagnosticDeriveError>`:
@@ -126,7 +126,7 @@ pub(crate) fn invalid_nested_attr(attr: &Attribute, nested: &NestedMeta) -> Diag
     }
 }
 
-/// Emit a error diagnostic for an invalid nested attribute (optionally performing additional
+/// Emit an error diagnostic for an invalid nested attribute (optionally performing additional
 /// decoration using the `FnOnce` passed in `diag`) and return `Err(ErrorHandled)`.
 ///
 /// For methods that return a `Result<_, DiagnosticDeriveError>`:
diff --git a/library/alloc/src/collections/mod.rs b/library/alloc/src/collections/mod.rs
index 161a375736c65..3e0b0f735508e 100644
--- a/library/alloc/src/collections/mod.rs
+++ b/library/alloc/src/collections/mod.rs
@@ -139,7 +139,7 @@ impl Display for TryReserveError {
                 " because the computed capacity exceeded the collection's maximum"
             }
             TryReserveErrorKind::AllocError { .. } => {
-                " because the memory allocator returned a error"
+                " because the memory allocator returned an error"
             }
         };
         fmt.write_str(reason)
diff --git a/src/test/ui/conditional-compilation/cfg_accessible-not_sure.rs b/src/test/ui/conditional-compilation/cfg_accessible-not_sure.rs
index d68acd2451fba..99a7949db173c 100644
--- a/src/test/ui/conditional-compilation/cfg_accessible-not_sure.rs
+++ b/src/test/ui/conditional-compilation/cfg_accessible-not_sure.rs
@@ -46,7 +46,7 @@ const C: bool = true;
 trait Trait {}
 impl dyn Trait { fn existing() {} }
 
-// FIXME: Should be a error for edition > 2015
+// FIXME: Should be an error for edition > 2015
 #[cfg_accessible(Trait::existing)] //~ ERROR not sure
 const A: bool = true;
 #[cfg_accessible(Trait::unresolved)] //~ ERROR not sure