diff --git a/Sources/MockingbirdGenerator/Generator/Templates/MockableTypeInitializerTemplate.swift b/Sources/MockingbirdGenerator/Generator/Templates/MockableTypeInitializerTemplate.swift
index b710fa30..e57a4829 100644
--- a/Sources/MockingbirdGenerator/Generator/Templates/MockableTypeInitializerTemplate.swift
+++ b/Sources/MockingbirdGenerator/Generator/Templates/MockableTypeInitializerTemplate.swift
@@ -80,37 +80,46 @@ struct MockableTypeInitializerTemplate: Template {
       supportingTypeDeclaration = ""
     }
     
-    let returnType: String
-    let returnStatement: String
-    let returnTypeDescription: String
-    
     let mockTypeScopedName =
       mockableTypeTemplate.createScopedName(with: containingTypeNames,
                                             genericTypeContext: genericTypeContext,
                                             suffix: "Mock")
     
+    let leadingTrivia: String
+    let attributes: [String]
+    let returnType: String
+    let returnStatement: String
+    
     if !mockableTypeTemplate.isAvailable {
       // Unavailable mocks do not generate real initializers.
+      leadingTrivia = ""
+      attributes = [mockableTypeTemplate.unavailableMockAttribute]
       returnType = mockTypeScopedName
       returnStatement = "fatalError()"
-      returnTypeDescription = mockableTypeTemplate.unavailableMockAttribute
     } else if !mockableTypeTemplate.shouldGenerateDefaultInitializer {
       // Requires an initializer proxy to create the partial class mock.
+      leadingTrivia = "/// Returns an abstract mock which should be initialized using `mock(\(mockableTypeTemplate.mockableType.name).self).initialize(…)`."
+      attributes = []
       returnType = "\(mockTypeScopedName).InitializerProxy.Type"
       returnStatement = "return \(mockTypeScopedName).InitializerProxy.self"
-      returnTypeDescription = "/// Returns an abstract mock which should be initialized using `mock(\(mockableTypeTemplate.mockableType.name).self).initialize(…)`."
     } else {
       // Does not require an initializer proxy.
+      leadingTrivia = "/// Returns a concrete mock of `\(mockableTypeTemplate.mockableType.name)`."
+      attributes = []
       returnType = mockTypeScopedName
       returnStatement = "return \(mockTypeScopedName)(sourceLocation: Mockingbird.SourceLocation(file, line))"
-      returnTypeDescription = "/// Returns a concrete mock of `\(mockableTypeTemplate.mockableType.name)`."
     }
     
-    return """
-    \(supportingTypeDeclaration)\(returnTypeDescription)
-    public func mock\(genericTypeConstraints)(_ type: \(metatype), file: StaticString = #file, line: UInt = #line) -> \(returnType) {
-      \(returnStatement)
-    }
+    let functionDeclaration = """
+    public func mock\(genericTypeConstraints)(_ type: \(metatype), file: StaticString = #file, line: UInt = #line) -> \(returnType)
     """
+    
+    return String(lines: [
+      supportingTypeDeclaration,
+      FunctionDefinitionTemplate(leadingTrivia: leadingTrivia,
+                                 attributes: attributes,
+                                 declaration: functionDeclaration,
+                                 body: returnStatement).render(),
+    ])
   }
 }
diff --git a/Sources/MockingbirdGenerator/Generator/Templates/Primitives/FunctionDefinitionTemplate.swift b/Sources/MockingbirdGenerator/Generator/Templates/Primitives/FunctionDefinitionTemplate.swift
index 615f8e81..49c70a4c 100644
--- a/Sources/MockingbirdGenerator/Generator/Templates/Primitives/FunctionDefinitionTemplate.swift
+++ b/Sources/MockingbirdGenerator/Generator/Templates/Primitives/FunctionDefinitionTemplate.swift
@@ -8,15 +8,18 @@
 import Foundation
 
 struct FunctionDefinitionTemplate: Template {
+  let leadingTrivia: String
   let attributes: [String]
   let declaration: String
   let genericConstraints: [String]
   let body: String
   
-  init(attributes: [String] = [],
+  init(leadingTrivia: String = "",
+       attributes: [String] = [],
        declaration: String,
        genericConstraints: [String] = [],
        body: String) {
+    self.leadingTrivia = leadingTrivia
     self.attributes = attributes
     self.declaration = declaration
     self.genericConstraints = genericConstraints
@@ -27,6 +30,7 @@ struct FunctionDefinitionTemplate: Template {
     let genericConstraintsString = genericConstraints.isEmpty ? "" :
       " where \(separated: genericConstraints)"
     return String(lines: [
+      leadingTrivia,
       attributes.filter({ !$0.isEmpty }).joined(separator: " "),
       declaration + genericConstraintsString + " " + BlockTemplate(body: body).render()
     ])
diff --git a/Sources/MockingbirdTestsHost/ExternalModuleTypes.swift b/Sources/MockingbirdTestsHost/ExternalModuleTypes.swift
index 1770cc82..0492a89b 100644
--- a/Sources/MockingbirdTestsHost/ExternalModuleTypes.swift
+++ b/Sources/MockingbirdTestsHost/ExternalModuleTypes.swift
@@ -8,6 +8,7 @@
 import Foundation
 import MockingbirdModuleTestsHost
 import MockingbirdShadowedTestsHost
+import CoreBluetooth
 
 protocol LocalPublicExternalProtocol: PublicExternalProtocol {}
 
@@ -17,6 +18,14 @@ class SubclassingExternalClass: ExternalClass {
   func internalMethod() {}
 }
 
+/// Cannot be mocked because of external inheritence without corresponding supporting source files.
+class SubclassingMissingExternalClass: CBCentralManager {}
+class SubclassingMissingExternalClassGeneric<T>: CBCentralManager {}
+protocol InheritingMissingExternalClass: CBCentralManager {}
+protocol InheritingMissingExternalClassGeneric: CBCentralManager {
+  associatedtype T
+}
+
 // MARK: - Inherited external initializer
 
 class SubclassingExternalClassWithInheritedIntializer: ExternalClassWithInitializer {