diff --git a/lib/Sema/TypeCheckProtocol.cpp b/lib/Sema/TypeCheckProtocol.cpp
index 36e3528563a39..46bf605b73701 100644
--- a/lib/Sema/TypeCheckProtocol.cpp
+++ b/lib/Sema/TypeCheckProtocol.cpp
@@ -912,8 +912,7 @@ RequirementMatch swift::matchWitness(
 
     case ThrownErrorSubtyping::Subtype:
       // If there were no type parameters, we're done.
-      if (!reqThrownError->hasTypeVariable() &&
-          !reqThrownError->hasTypeParameter())
+      if (!reqThrownError->hasTypeParameter())
         break;
 
       LLVM_FALLTHROUGH;
diff --git a/test/decl/protocol/conforms/typed_throws.swift b/test/decl/protocol/conforms/typed_throws.swift
index 352312819c4f5..85306c4ae5a5f 100644
--- a/test/decl/protocol/conforms/typed_throws.swift
+++ b/test/decl/protocol/conforms/typed_throws.swift
@@ -77,3 +77,17 @@ public protocol HasRethrowingMap: Sequence {
 }
 
 extension Array: HasRethrowingMap {}
+
+// rdar://149438520 -- incorrect handling of subtype relation between type parameter and Never
+protocol DependentThrowing {
+  associatedtype E: Error
+  func f() throws(E)
+}
+
+extension DependentThrowing {
+  func f() {}
+}
+
+struct DefaultDependentThrowing: DependentThrowing {
+  typealias E = Error
+}
\ No newline at end of file