diff --git a/CHANGELOG b/CHANGELOG
index 4662de0e..80286a15 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,9 @@
 # Factory Changelog
 
+### 1.2.4
+
+* Recursive lock required in scope resolution
+
 ### 1.2.3
 
 * Streamline critical path through scope caching mechanism
diff --git a/Sources/Factory/Factory.swift b/Sources/Factory/Factory.swift
index beaac786..87a9b621 100644
--- a/Sources/Factory/Factory.swift
+++ b/Sources/Factory/Factory.swift
@@ -109,7 +109,6 @@ public struct ParameterFactory<P, T> {
 
 /// Empty convenience class for user dependencies.
 public class Container: SharedContainer {
-
 }
 
 /// Base class for all containers.
@@ -227,7 +226,7 @@ open class SharedContainer {
             }
         }
 
-        private var lock = NSLock()
+        private var lock = NSRecursiveLock()
         private var cache: [UUID:AnyBox] = .init(minimumCapacity: 64)
 
     }
diff --git a/Tests/FactoryTests/FactoryDefectTests.swift b/Tests/FactoryTests/FactoryDefectTests.swift
index 0c8e1318..4290de26 100644
--- a/Tests/FactoryTests/FactoryDefectTests.swift
+++ b/Tests/FactoryTests/FactoryDefectTests.swift
@@ -50,8 +50,34 @@ final class FactoryDefectTests: XCTestCase {
         XCTAssertNil(service1.service)
     }
 
+    // Nested injection when both are on the same scope locks thread. If this test passes then thread wasn't locked...
+    func testSingletondScopeLocking() throws {
+        let service1: LockingTestA? = Container.lockingTestA()
+        XCTAssertNotNil(service1)
+        let service2: LockingTestA? = Container.lockingTestA()
+        XCTAssertNotNil(service2)
+        let text1 = Container.singletonService().text()
+        let text2 = Container.singletonService().text()
+        XCTAssertTrue(text1 == text2)
+    }
+
 }
 
-private class TestLazyInjectionOccursOnce {
+fileprivate class TestLazyInjectionOccursOnce {
     @LazyInjected(Container.nilSService) var service
 }
+
+extension Container {
+    fileprivate static var lockingTestA = Factory(scope: .singleton) { LockingTestA() }
+    fileprivate static var lockingTestB = Factory(scope: .singleton) { LockingTestB() }
+}
+
+// classes for recursive resolution test
+fileprivate class LockingTestA {
+    @Injected(Container.lockingTestB) var b: LockingTestB
+    init() {}
+}
+
+fileprivate class LockingTestB {
+    init() {}
+}
diff --git a/Tests/FactoryTests/FactoryScopeTests.swift b/Tests/FactoryTests/FactoryScopeTests.swift
index 44a93273..f4d51a0f 100644
--- a/Tests/FactoryTests/FactoryScopeTests.swift
+++ b/Tests/FactoryTests/FactoryScopeTests.swift
@@ -6,7 +6,7 @@ final class FactoryScopeTests: XCTestCase {
     override func setUp() {
         super.setUp()
         Container.Registrations.reset()
-        Container.Scope.reset()
+        Container.Scope.reset(includingSingletons: true)
     }
 
     func testUniqueScope() throws {