diff --git a/Sources/FrontEnd/TypedProgram.swift b/Sources/FrontEnd/TypedProgram.swift
index 28b0b023d..3e643d45d 100644
--- a/Sources/FrontEnd/TypedProgram.swift
+++ b/Sources/FrontEnd/TypedProgram.swift
@@ -129,7 +129,7 @@ public struct TypedProgram {
   }
 
   /// The type checking of a collection of source files.
-  private final class TypeCheckTask: Operation {
+  private final class TypeCheckTask: Operation, @unchecked Sendable {
 
     /// The sources to check.
     private let sources: [TranslationUnit.ID]
diff --git a/StandardLibrary/Sources/Array.hylo b/StandardLibrary/Sources/Array.hylo
index 4c1d61e88..dd8db8007 100644
--- a/StandardLibrary/Sources/Array.hylo
+++ b/StandardLibrary/Sources/Array.hylo
@@ -1,5 +1,5 @@
 /// An ordered, random-access collection.
-public type Array<Element: SemiRegular>: SemiRegular {
+public type Array<Element: Movable & Deinitializable>: Movable, Deinitializable {
 
   /// The out-of-line storage of the array.
   ///
@@ -207,7 +207,7 @@ public type Array<Element: SemiRegular>: SemiRegular {
 
 }
 
-public conformance Array: Equatable {
+public conformance Array: Equatable where Element: Equatable {
 
   /// Returns `true` iff `other` has an equivalent value.
   public fun infix== (_ other: Self) -> Bool {
diff --git a/StandardLibrary/Sources/Core/Range.hylo b/StandardLibrary/Sources/Core/Range.hylo
index cb3059b0e..04e8b4566 100644
--- a/StandardLibrary/Sources/Core/Range.hylo
+++ b/StandardLibrary/Sources/Core/Range.hylo
@@ -1,5 +1,5 @@
 /// A half-open interval from a lower bound up to, but not including, an uppor bound.
-public type Range<Bound: SemiRegular & Comparable> {
+public type Range<Bound: Movable & Deinitializable & Comparable> {
 
   // TODO: private(set)
   /// The minimum value included in `self`.
diff --git a/StandardLibrary/Sources/Core/Regular.hylo b/StandardLibrary/Sources/Core/Regular.hylo
index e3a1ac171..3cfed1a8b 100644
--- a/StandardLibrary/Sources/Core/Regular.hylo
+++ b/StandardLibrary/Sources/Core/Regular.hylo
@@ -3,9 +3,9 @@
 ///
 /// - Move is value-preserving.
 /// - Destruction has no side-effects.
-public trait SemiRegular: Deinitializable, Movable, Equatable {}
+public trait SemiRegular: Copyable, Deinitializable {}
 
 /// Regular types (roughly per Stepanov).
 ///
 /// Copies have equal value.
-public trait Regular: SemiRegular, Copyable {}
+public trait Regular: SemiRegular, Equatable {}
diff --git a/Tests/HyloTests/TestCases/TypeChecking/AbstractType.hylo b/Tests/HyloTests/TestCases/TypeChecking/AbstractType.hylo
index d36223a41..dc2351bfa 100644
--- a/Tests/HyloTests/TestCases/TypeChecking/AbstractType.hylo
+++ b/Tests/HyloTests/TestCases/TypeChecking/AbstractType.hylo
@@ -1,14 +1,19 @@
 //- typeCheck expecting: .success
 
-trait P: SemiRegular {
-  type T: SemiRegular
-  type U: SemiRegular
+// Our SemiRegular when this test was written wasn't the genuine
+// SemiRegular but was being depended on by this test, so rephrasing
+// it here.
+trait LegacySemiRegular: Deinitializable, Movable, Equatable {}
+
+trait P: LegacySemiRegular {
+  type T: LegacySemiRegular
+  type U: LegacySemiRegular
 
   fun t(_ x: T)
   fun u(_ x: U)
 }
 
-trait Q: SemiRegular {
+trait Q: LegacySemiRegular {
   type V: P
   property v: V { let }
 }