diff --git a/__tests__/saveOnly.test.ts b/__tests__/saveOnly.test.ts
index 5a7f8b0..e670c90 100644
--- a/__tests__/saveOnly.test.ts
+++ b/__tests__/saveOnly.test.ts
@@ -11,12 +11,12 @@ jest.mock("@actions/cache");
 jest.mock("../src/utils/actionUtils");
 
 beforeAll(() => {
-    jest.spyOn(core, "getInput").mockImplementation((name, options) => {
-        return jest.requireActual("@actions/core").getInput(name, options);
+    jest.spyOn(core, "getInput").mockImplementation(name => {
+        return testUtils.getInput(name);
     });
 
-    jest.spyOn(core, "setOutput").mockImplementation((key, value) => {
-        return jest.requireActual("@actions/core").getInput(key, value);
+    jest.spyOn(core, "getState").mockImplementation(name => {
+        return jest.requireActual("@actions/core").getState(name);
     });
 
     jest.spyOn(actionUtils, "getInputAsArray").mockImplementation(
diff --git a/__tests__/stateProvider.test.ts b/__tests__/stateProvider.test.ts
index 255b5fb..540e065 100644
--- a/__tests__/stateProvider.test.ts
+++ b/__tests__/stateProvider.test.ts
@@ -1,11 +1,12 @@
 import * as core from "@actions/core";
 
-import { Events, RefKey, State } from "../src/constants";
+import { Events, Inputs, RefKey, State } from "../src/constants";
 import {
     IStateProvider,
     NullStateProvider,
     StateProvider
 } from "../src/stateProvider";
+import * as testUtils from "../src/utils/testUtils";
 
 jest.mock("@actions/core");
 
@@ -58,32 +59,43 @@ test("StateProvider saves states", async () => {
 });
 
 test("NullStateProvider saves outputs", async () => {
+    const states = new Map<string, string>();
+
+    const getInputMock = jest
+        .spyOn(core, "getInput")
+        .mockImplementation(key => testUtils.getInput(key));
+
     const getStateMock = jest
         .spyOn(core, "getState")
-        .mockImplementation(name =>
-            jest.requireActual("@actions/core").getState(name)
-        );
+        .mockImplementation(key => {
+            return jest.requireActual("@actions/core").getState(key);
+        });
 
     const setOutputMock = jest
         .spyOn(core, "setOutput")
         .mockImplementation((key, value) => {
-            return jest.requireActual("@actions/core").setOutput(key, value);
+            states.set(key, value);
         });
 
     const saveStateMock = jest
         .spyOn(core, "saveState")
         .mockImplementation((key, value) => {
-            return jest.requireActual("@actions/core").saveState(key, value);
+            states.set(key, value);
         });
 
     const cacheMatchedKey = "node-cache";
+    const cachePrimaryKey = "primary-key";
     const nullStateProvider: IStateProvider = new NullStateProvider();
-    nullStateProvider.setState(State.CacheMatchedKey, "outputValue");
-    nullStateProvider.setState(State.CachePrimaryKey, cacheMatchedKey);
-    nullStateProvider.getState("outputKey");
-    nullStateProvider.getCacheState();
+    testUtils.setInput(Inputs.Key, cachePrimaryKey);
+    nullStateProvider.setState(State.CachePrimaryKey, cachePrimaryKey);
+    nullStateProvider.setState(State.CacheMatchedKey, cacheMatchedKey);
+    const output1 = nullStateProvider.getState(State.CachePrimaryKey);
+    const output2 = nullStateProvider.getCacheState();
 
     expect(getStateMock).toHaveBeenCalledTimes(0);
+    expect(getInputMock).toHaveBeenCalledTimes(1);
+    expect(output1).toBe("primary-key");
+    expect(output2).toBe(undefined);
     expect(setOutputMock).toHaveBeenCalledTimes(2);
     expect(saveStateMock).toHaveBeenCalledTimes(0);
 });
diff --git a/dist/restore-only/index.js b/dist/restore-only/index.js
index f676abb..0daba23 100644
--- a/dist/restore-only/index.js
+++ b/dist/restore-only/index.js
@@ -9413,15 +9413,24 @@ exports.StateProvider = StateProvider;
 class NullStateProvider extends StateProviderBase {
     constructor() {
         super(...arguments);
+        this.stateToInputMap = new Map([
+            [constants_1.State.CachePrimaryKey, constants_1.Inputs.Key]
+        ]);
         this.stateToOutputMap = new Map([
             [constants_1.State.CacheMatchedKey, constants_1.Outputs.CacheMatchedKey],
             [constants_1.State.CachePrimaryKey, constants_1.Outputs.CachePrimaryKey]
         ]);
         this.setState = (key, value) => {
-            core.setOutput(this.stateToOutputMap.get(key), value);
+            if (this.stateToOutputMap.has(key)) {
+                core.setOutput(this.stateToOutputMap.get(key), value);
+            }
+        };
+        this.getState = (key) => {
+            if (!this.stateToInputMap.has(key)) {
+                return "";
+            }
+            return core.getInput(this.stateToInputMap.get(key));
         };
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        this.getState = (key) => "";
     }
 }
 exports.NullStateProvider = NullStateProvider;
diff --git a/dist/restore/index.js b/dist/restore/index.js
index 6415478..0f028df 100644
--- a/dist/restore/index.js
+++ b/dist/restore/index.js
@@ -9413,15 +9413,24 @@ exports.StateProvider = StateProvider;
 class NullStateProvider extends StateProviderBase {
     constructor() {
         super(...arguments);
+        this.stateToInputMap = new Map([
+            [constants_1.State.CachePrimaryKey, constants_1.Inputs.Key]
+        ]);
         this.stateToOutputMap = new Map([
             [constants_1.State.CacheMatchedKey, constants_1.Outputs.CacheMatchedKey],
             [constants_1.State.CachePrimaryKey, constants_1.Outputs.CachePrimaryKey]
         ]);
         this.setState = (key, value) => {
-            core.setOutput(this.stateToOutputMap.get(key), value);
+            if (this.stateToOutputMap.has(key)) {
+                core.setOutput(this.stateToOutputMap.get(key), value);
+            }
+        };
+        this.getState = (key) => {
+            if (!this.stateToInputMap.has(key)) {
+                return "";
+            }
+            return core.getInput(this.stateToInputMap.get(key));
         };
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        this.getState = (key) => "";
     }
 }
 exports.NullStateProvider = NullStateProvider;
diff --git a/dist/save-only/index.js b/dist/save-only/index.js
index 0d3295c..f5844f1 100644
--- a/dist/save-only/index.js
+++ b/dist/save-only/index.js
@@ -9469,15 +9469,24 @@ exports.StateProvider = StateProvider;
 class NullStateProvider extends StateProviderBase {
     constructor() {
         super(...arguments);
+        this.stateToInputMap = new Map([
+            [constants_1.State.CachePrimaryKey, constants_1.Inputs.Key]
+        ]);
         this.stateToOutputMap = new Map([
             [constants_1.State.CacheMatchedKey, constants_1.Outputs.CacheMatchedKey],
             [constants_1.State.CachePrimaryKey, constants_1.Outputs.CachePrimaryKey]
         ]);
         this.setState = (key, value) => {
-            core.setOutput(this.stateToOutputMap.get(key), value);
+            if (this.stateToOutputMap.has(key)) {
+                core.setOutput(this.stateToOutputMap.get(key), value);
+            }
+        };
+        this.getState = (key) => {
+            if (!this.stateToInputMap.has(key)) {
+                return "";
+            }
+            return core.getInput(this.stateToInputMap.get(key));
         };
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        this.getState = (key) => "";
     }
 }
 exports.NullStateProvider = NullStateProvider;
@@ -41164,8 +41173,7 @@ function saveImpl(stateProvider) {
             }
             // If restore has stored a primary key in state, reuse that
             // Else re-evaluate from inputs
-            const primaryKey = stateProvider.getState(constants_1.State.CachePrimaryKey) ||
-                core.getInput(constants_1.Inputs.Key);
+            const primaryKey = stateProvider.getState(constants_1.State.CachePrimaryKey);
             if (!primaryKey) {
                 utils.logWarning(`Key is not specified.`);
                 return;
diff --git a/dist/save/index.js b/dist/save/index.js
index 1b0a733..8b982f0 100644
--- a/dist/save/index.js
+++ b/dist/save/index.js
@@ -9413,15 +9413,24 @@ exports.StateProvider = StateProvider;
 class NullStateProvider extends StateProviderBase {
     constructor() {
         super(...arguments);
+        this.stateToInputMap = new Map([
+            [constants_1.State.CachePrimaryKey, constants_1.Inputs.Key]
+        ]);
         this.stateToOutputMap = new Map([
             [constants_1.State.CacheMatchedKey, constants_1.Outputs.CacheMatchedKey],
             [constants_1.State.CachePrimaryKey, constants_1.Outputs.CachePrimaryKey]
         ]);
         this.setState = (key, value) => {
-            core.setOutput(this.stateToOutputMap.get(key), value);
+            if (this.stateToOutputMap.has(key)) {
+                core.setOutput(this.stateToOutputMap.get(key), value);
+            }
+        };
+        this.getState = (key) => {
+            if (!this.stateToInputMap.has(key)) {
+                return "";
+            }
+            return core.getInput(this.stateToInputMap.get(key));
         };
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        this.getState = (key) => "";
     }
 }
 exports.NullStateProvider = NullStateProvider;
@@ -41108,8 +41117,7 @@ function saveImpl(stateProvider) {
             }
             // If restore has stored a primary key in state, reuse that
             // Else re-evaluate from inputs
-            const primaryKey = stateProvider.getState(constants_1.State.CachePrimaryKey) ||
-                core.getInput(constants_1.Inputs.Key);
+            const primaryKey = stateProvider.getState(constants_1.State.CachePrimaryKey);
             if (!primaryKey) {
                 utils.logWarning(`Key is not specified.`);
                 return;
diff --git a/src/saveImpl.ts b/src/saveImpl.ts
index 5fd4513..f589e76 100644
--- a/src/saveImpl.ts
+++ b/src/saveImpl.ts
@@ -28,9 +28,7 @@ async function saveImpl(stateProvider: IStateProvider): Promise<number | void> {
 
         // If restore has stored a primary key in state, reuse that
         // Else re-evaluate from inputs
-        const primaryKey =
-            stateProvider.getState(State.CachePrimaryKey) ||
-            core.getInput(Inputs.Key);
+        const primaryKey = stateProvider.getState(State.CachePrimaryKey);
 
         if (!primaryKey) {
             utils.logWarning(`Key is not specified.`);
diff --git a/src/stateProvider.ts b/src/stateProvider.ts
index beb41e5..131ec69 100644
--- a/src/stateProvider.ts
+++ b/src/stateProvider.ts
@@ -1,6 +1,6 @@
 import * as core from "@actions/core";
 
-import { Outputs, State } from "./constants";
+import { Inputs, Outputs, State } from "./constants";
 
 export interface IStateProvider {
     setState(key: string, value: string): void;
@@ -33,14 +33,25 @@ export class StateProvider extends StateProviderBase {
 }
 
 export class NullStateProvider extends StateProviderBase {
+    stateToInputMap = new Map<string, string>([
+        [State.CachePrimaryKey, Inputs.Key]
+    ]);
+
     stateToOutputMap = new Map<string, string>([
         [State.CacheMatchedKey, Outputs.CacheMatchedKey],
         [State.CachePrimaryKey, Outputs.CachePrimaryKey]
     ]);
 
     setState = (key: string, value: string) => {
-        core.setOutput(this.stateToOutputMap.get(key) as string, value);
+        if (this.stateToOutputMap.has(key)) {
+            core.setOutput(this.stateToOutputMap.get(key) as string, value);
+        }
+    };
+
+    getState = (key: string) => {
+        if (!this.stateToInputMap.has(key)) {
+            return "";
+        }
+        return core.getInput(this.stateToInputMap.get(key) as string);
     };
-    // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    getState = (key: string) => "";
 }
diff --git a/src/utils/testUtils.ts b/src/utils/testUtils.ts
index c0a3f43..845cee9 100644
--- a/src/utils/testUtils.ts
+++ b/src/utils/testUtils.ts
@@ -9,6 +9,10 @@ export function setInput(name: string, value: string): void {
     process.env[getInputName(name)] = value;
 }
 
+export function getInput(name: string): string {
+    return process.env[getInputName(name)] as string;
+}
+
 interface CacheInput {
     path: string;
     key: string;