diff --git a/packages/injectable/core/src/dependency-injection-container/createContainer.js b/packages/injectable/core/src/dependency-injection-container/createContainer.js
index 1e25b9ab..afbef733 100644
--- a/packages/injectable/core/src/dependency-injection-container/createContainer.js
+++ b/packages/injectable/core/src/dependency-injection-container/createContainer.js
@@ -7,26 +7,22 @@ import { purgeInstancesFor } from './purgeInstances';
 import { deregisterFor } from './deregister';
 import { overrideFor, unoverrideFor } from './override';
 import { decorateFor, decorateFunctionFor } from './decorate';
+import isInjectable from '../getInjectable/isInjectable';
 
 export default containerId => {
-  let injectableMap = new Map();
+  let injectableSet = new Set();
   let overridingInjectables = new Map();
   let sideEffectsArePrevented = false;
   let alreadyInjected = new Set();
+  let injectablesWithPermittedSideEffects = new Set();
 
   const injectableAndRegistrationContext = new Map();
   const instancesByInjectableMap = new Map();
-  const injectableIdsByInjectionToken = new Map();
-
-  const getInjectablesHavingInjectionToken =
-    getInjectablesHavingInjectionTokenFor({
-      injectableMap,
-      injectableIdsByInjectionToken,
-    });
+  const injectablesByInjectionToken = new Map();
 
   const getRelatedInjectables = getRelatedInjectablesFor({
-    injectableMap,
-    getInjectablesHavingInjectionToken,
+    injectablesByInjectionToken,
+    injectableSet,
   });
 
   const containerRootContextItem = { injectable: { id: containerId } };
@@ -52,6 +48,11 @@ export default containerId => {
     injectMany: nonDecoratedPrivateInjectMany,
   });
 
+  const getSideEffectsArePrevented = injectable =>
+    sideEffectsArePrevented &&
+    injectable.causesSideEffects &&
+    !injectablesWithPermittedSideEffects.has(injectable);
+
   const privateInject = privateInjectFor({
     getRelatedInjectables,
     alreadyInjected,
@@ -59,8 +60,7 @@ export default containerId => {
     instancesByInjectableMap,
     injectableAndRegistrationContext,
     injectMany: nonDecoratedPrivateInjectMany,
-    // Todo: get rid of function usage.
-    getSideEffectsArePrevented: () => sideEffectsArePrevented,
+    getSideEffectsArePrevented,
     getDi: () => privateDi,
   });
 
@@ -73,9 +73,9 @@ export default containerId => {
   );
 
   const registerSingle = registerSingleFor({
-    injectableMap,
+    injectableSet,
     instancesByInjectableMap,
-    injectableIdsByInjectionToken,
+    injectablesByInjectionToken,
   });
 
   const purgeInstances = purgeInstancesFor({
@@ -87,9 +87,9 @@ export default containerId => {
 
   const deregister = deregisterFor({
     injectMany: nonDecoratedPrivateInjectMany,
-    injectableMap,
+    injectableSet,
     injectableAndRegistrationContext,
-    injectableIdsByInjectionToken,
+    injectablesByInjectionToken,
     overridingInjectables,
     purgeInstances,
     // Todo: get rid of function usage.
@@ -131,7 +131,7 @@ export default containerId => {
     },
 
     permitSideEffects: alias => {
-      getRelatedInjectables(alias)[0].permitSideEffects();
+      injectablesWithPermittedSideEffects.add(alias);
     },
 
     purge: purgeInstances,
@@ -171,35 +171,14 @@ export default containerId => {
   return publicDi;
 };
 
-const getInjectablesHavingInjectionTokenFor =
-  ({ injectableMap, injectableIdsByInjectionToken }) =>
-  alias => {
-    const idSetForInjectablesHavingInjectionToken =
-      injectableIdsByInjectionToken.get(alias.id);
-
-    const idsForInjectablesHavingInjectionToken =
-      idSetForInjectablesHavingInjectionToken
-        ? [...idSetForInjectablesHavingInjectionToken.values()]
-        : [];
-
-    return idsForInjectablesHavingInjectionToken.map(injectableId =>
-      injectableMap.get(injectableId),
-    );
-  };
-
 const getRelatedInjectablesFor =
-  ({ injectableMap, getInjectablesHavingInjectionToken }) =>
-  alias => {
-    const injectable = injectableMap.get(alias.id);
-
-    const injectablesHavingInjectionToken = getInjectablesHavingInjectionToken(
-      alias,
-    ).filter(x => x.id !== alias.id);
-
-    return injectable
-      ? [injectable, ...injectablesHavingInjectionToken]
-      : injectablesHavingInjectionToken;
-  };
+  ({ injectablesByInjectionToken, injectableSet }) =>
+  alias =>
+    isInjectable(alias)
+      ? injectableSet.has(alias)
+        ? [alias]
+        : []
+      : [...(injectablesByInjectionToken.get(alias)?.values() || [])];
 
 export const registrationCallbackToken = getInjectionToken({
   id: 'registration-callback-token',
diff --git a/packages/injectable/core/src/dependency-injection-container/deregister.js b/packages/injectable/core/src/dependency-injection-container/deregister.js
index 844579c3..eb24745c 100644
--- a/packages/injectable/core/src/dependency-injection-container/deregister.js
+++ b/packages/injectable/core/src/dependency-injection-container/deregister.js
@@ -3,9 +3,9 @@ import { deregistrationCallbackToken } from './createContainer';
 export const deregisterFor =
   ({
     injectMany,
-    injectableMap,
+    injectableSet,
     injectableAndRegistrationContext,
-    injectableIdsByInjectionToken,
+    injectablesByInjectionToken,
     overridingInjectables,
     purgeInstances,
     // Todo: get rid of function usage.
@@ -23,9 +23,9 @@ export const deregisterFor =
     const di = getDi();
 
     const deregisterSingle = deregisterSingleFor({
-      injectableMap,
+      injectableSet,
       injectableAndRegistrationContext,
-      injectableIdsByInjectionToken,
+      injectablesByInjectionToken,
       overridingInjectables,
       purgeInstances,
       di,
@@ -38,25 +38,23 @@ export const deregisterFor =
 
 export const deregisterSingleFor =
   ({
-    injectableMap,
+    injectableSet,
     injectableAndRegistrationContext,
-    injectableIdsByInjectionToken,
+    injectablesByInjectionToken,
     overridingInjectables,
     purgeInstances,
     di,
   }) =>
-  alias => {
-    const relatedInjectable = injectableMap.get(alias.id);
-
-    if (!relatedInjectable) {
+  injectable => {
+    if (!injectableSet.has(injectable)) {
       throw new Error(
-        `Tried to deregister non-registered injectable "${alias.id}".`,
+        `Tried to deregister non-registered injectable "${injectable.id}".`,
       );
     }
 
     [...injectableAndRegistrationContext.entries()]
       .filter(([, context]) =>
-        context.find(contextItem => contextItem.injectable.id === alias.id),
+        context.find(contextItem => contextItem.injectable === injectable),
       )
       .map(x => x[0])
       .forEach(injectable => {
@@ -64,17 +62,15 @@ export const deregisterSingleFor =
         di.deregister(injectable);
       });
 
-    purgeInstances(alias);
-
-    injectableMap.delete(alias.id);
-
-    if (alias.injectionToken) {
-      const tokenId = alias.injectionToken.id;
+    purgeInstances(injectable);
 
-      const injectableIdSet = injectableIdsByInjectionToken.get(tokenId);
+    injectableSet.delete(injectable);
 
-      injectableIdSet.delete(alias.id);
+    if (injectable.injectionToken) {
+      injectablesByInjectionToken
+        .get(injectable.injectionToken)
+        .delete(injectable);
     }
 
-    overridingInjectables.delete(alias.id);
+    overridingInjectables.delete(injectable);
   };
diff --git a/packages/injectable/core/src/dependency-injection-container/inject.js b/packages/injectable/core/src/dependency-injection-container/inject.js
index 5f2dcb70..d34e539d 100644
--- a/packages/injectable/core/src/dependency-injection-container/inject.js
+++ b/packages/injectable/core/src/dependency-injection-container/inject.js
@@ -31,15 +31,14 @@ export const privateInjectFor = ({
 
       const originalInjectable = getRelatedInjectables(alias)[0];
 
-      alreadyInjected.add(originalInjectable.id);
+      alreadyInjected.add(originalInjectable);
 
-      const overriddenInjectable = overridingInjectables.get(
-        originalInjectable.id,
-      );
+      const overriddenInjectable =
+        overridingInjectables.get(originalInjectable);
 
       const injectable = overriddenInjectable || originalInjectable;
 
-      if (getSideEffectsArePrevented() && injectable.causesSideEffects) {
+      if (getSideEffectsArePrevented(injectable)) {
         throw new Error(
           `Tried to inject "${[...context, { injectable }]
             .map(item => item.injectable.id)
@@ -100,7 +99,8 @@ const getInstance = ({
   ];
 
   const instanceMap = instancesByInjectableMap.get(
-    injectableToBeInstantiated.id,
+    injectableToBeInstantiated.overriddenInjectable ||
+      injectableToBeInstantiated,
   );
 
   const minimalDi = {
diff --git a/packages/injectable/core/src/dependency-injection-container/override.js b/packages/injectable/core/src/dependency-injection-container/override.js
index 90cdbac6..61f9dd5b 100644
--- a/packages/injectable/core/src/dependency-injection-container/override.js
+++ b/packages/injectable/core/src/dependency-injection-container/override.js
@@ -25,7 +25,7 @@ export const overrideFor =
       );
     }
 
-    if (alreadyInjected.has(alias.id)) {
+    if (alreadyInjected.has(alias)) {
       throw new Error(
         `Tried to override injectable "${alias.id}", but it was already injected.`,
       );
@@ -33,8 +33,9 @@ export const overrideFor =
 
     const originalInjectable = relatedInjectables[0];
 
-    overridingInjectables.set(originalInjectable.id, {
+    overridingInjectables.set(originalInjectable, {
       ...originalInjectable,
+      overriddenInjectable: originalInjectable,
       causesSideEffects: false,
       instantiate: instantiateStub,
     });
@@ -42,6 +43,6 @@ export const overrideFor =
 
 export const unoverrideFor =
   ({ overridingInjectables }) =>
-  alias => {
-    overridingInjectables.delete(alias.id);
+  injectable => {
+    overridingInjectables.delete(injectable);
   };
diff --git a/packages/injectable/core/src/dependency-injection-container/purgeInstances.js b/packages/injectable/core/src/dependency-injection-container/purgeInstances.js
index 2ca77c1b..a6ae5788 100644
--- a/packages/injectable/core/src/dependency-injection-container/purgeInstances.js
+++ b/packages/injectable/core/src/dependency-injection-container/purgeInstances.js
@@ -3,5 +3,5 @@ export const purgeInstancesFor =
   alias => {
     const injectable = getRelatedInjectables(alias)[0];
 
-    instancesByInjectableMap.get(injectable.id).clear();
+    instancesByInjectableMap.get(injectable).clear();
   };
diff --git a/packages/injectable/core/src/dependency-injection-container/register.js b/packages/injectable/core/src/dependency-injection-container/register.js
index f9e6e78e..3a12daa4 100644
--- a/packages/injectable/core/src/dependency-injection-container/register.js
+++ b/packages/injectable/core/src/dependency-injection-container/register.js
@@ -17,43 +17,31 @@ export const registerFor =
   };
 
 export const registerSingleFor =
-  ({
-    injectableMap,
-    instancesByInjectableMap,
-    injectableIdsByInjectionToken,
-  }) =>
-  externalInjectable => {
-    let injectableId = externalInjectable.id;
+  ({ injectableSet, instancesByInjectableMap, injectablesByInjectionToken }) =>
+  injectable => {
+    let injectableId = injectable.id;
 
     if (!injectableId) {
       throw new Error('Tried to register injectable without ID.');
     }
 
-    if (injectableMap.has(injectableId)) {
+    if ([...injectableSet.values()].find(x => x.id === injectableId)) {
       throw new Error(
         `Tried to register multiple injectables for ID "${injectableId}"`,
       );
     }
 
-    const internalInjectable = {
-      ...externalInjectable,
+    injectableSet.add(injectable);
+    instancesByInjectableMap.set(injectable, new Map());
 
-      permitSideEffects: function () {
-        this.causesSideEffects = false;
-      },
-    };
+    if (injectable.injectionToken) {
+      const token = injectable.injectionToken;
 
-    injectableMap.set(internalInjectable.id, internalInjectable);
-    instancesByInjectableMap.set(internalInjectable.id, new Map());
+      const injectablesSet =
+        injectablesByInjectionToken.get(token) || new Set();
 
-    if (externalInjectable.injectionToken) {
-      const tokenId = externalInjectable.injectionToken.id;
+      injectablesSet.add(injectable);
 
-      const injectableIdsSet =
-        injectableIdsByInjectionToken.get(tokenId) || new Set();
-
-      injectableIdsSet.add(injectableId);
-
-      injectableIdsByInjectionToken.set(tokenId, injectableIdsSet);
+      injectablesByInjectionToken.set(token, injectablesSet);
     }
   };