diff --git a/__tests__/find-pypy.test.ts b/__tests__/find-pypy.test.ts
index b9c6599f..ddf7ebcf 100644
--- a/__tests__/find-pypy.test.ts
+++ b/__tests__/find-pypy.test.ts
@@ -49,23 +49,6 @@ describe('parsePyPyVersion', () => {
   });
 });
 
-describe('validateVersion', () => {
-  it.each([
-    ['v7.3.3', true],
-    ['v7.3.x', true],
-    ['v7.x', true],
-    ['x', true],
-    ['v7.3.3-rc.1', true],
-    ['nightly', true],
-    ['v7.3.b', false],
-    ['3.6', true],
-    ['3.b', false],
-    ['3', true]
-  ])('%s -> %s', (input, expected) => {
-    expect(validateVersion(input)).toEqual(expected);
-  });
-});
-
 describe('getPyPyVersionFromPath', () => {
   it('/fake/toolcache/PyPy/3.6.5/x64 -> 3.6.5', () => {
     expect(getPyPyVersionFromPath('/fake/toolcache/PyPy/3.6.5/x64')).toEqual(
@@ -223,6 +206,12 @@ describe('findPyPyVersion', () => {
     ).rejects.toThrow();
   });
 
+  it('throw on invalid input format pypy3.7-7.3.x', async () => {
+    await expect(
+      finder.findPyPyVersion('pypy3.7-v7.3.x', architecture)
+    ).rejects.toThrow();
+  });
+
   it('found and install successfully', async () => {
     spyCacheDir = jest.spyOn(tc, 'cacheDir');
     spyCacheDir.mockImplementation(() =>
@@ -240,9 +229,9 @@ describe('findPyPyVersion', () => {
 
   it('throw if release is not found', async () => {
     await expect(
-      finder.findPyPyVersion('pypy3.7-v7.3.x', architecture)
+      finder.findPyPyVersion('pypy-3.7-v7.5.x', architecture)
     ).rejects.toThrowError(
-      "Invalid 'version' property for PyPy. PyPy version should be specified as 'pypy-<python-version>'. See README for examples and documentation."
+      `PyPy version 3.7 (v7.5.x) with arch ${architecture} not found`
     );
   });
 });
diff --git a/__tests__/utils.test.ts b/__tests__/utils.test.ts
new file mode 100644
index 00000000..9463849f
--- /dev/null
+++ b/__tests__/utils.test.ts
@@ -0,0 +1,34 @@
+import {
+  validateVersion,
+  validatePythonVersionFormatForPyPy
+} from '../src/utils';
+
+describe('validatePythonVersionFormatForPyPy', () => {
+  it.each([
+    ['3.6', true],
+    ['3.7', true],
+    ['3.6.x', false],
+    ['3.7.x', false],
+    ['3.x', false],
+    ['3', false]
+  ])('%s -> %s', (input, expected) => {
+    expect(validatePythonVersionFormatForPyPy(input)).toEqual(expected);
+  });
+});
+
+describe('validateVersion', () => {
+  it.each([
+    ['v7.3.3', true],
+    ['v7.3.x', true],
+    ['v7.x', true],
+    ['x', true],
+    ['v7.3.3-rc.1', true],
+    ['nightly', true],
+    ['v7.3.b', false],
+    ['3.6', true],
+    ['3.b', false],
+    ['3', true]
+  ])('%s -> %s', (input, expected) => {
+    expect(validateVersion(input)).toEqual(expected);
+  });
+});
diff --git a/dist/index.js b/dist/index.js
index 4992e541..3fe97152 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -1168,6 +1168,9 @@ function parsePyPyVersion(versionSpec) {
     if (!utils_1.validateVersion(pythonVersion) || !utils_1.validateVersion(pypyVersion)) {
         throw new Error("Invalid 'version' property for PyPy. Both Python version and PyPy versions should satisfy SemVer notation. See README for examples and documentation.");
     }
+    if (!utils_1.validatePythonVersionFormatForPyPy(pythonVersion)) {
+        throw new Error("Invalid format of Python version for PyPy. Python version should be specified in format 'x.y'. See README for examples and documentation.");
+    }
     return {
         pypyVersion: pypyVersion,
         pythonVersion: pythonVersion
@@ -2375,6 +2378,16 @@ function writeExactPyPyVersionFile(installDir, resolvedPyPyVersion) {
     fs_1.default.writeFileSync(pypyFilePath, resolvedPyPyVersion);
 }
 exports.writeExactPyPyVersionFile = writeExactPyPyVersionFile;
+/**
+ * Python version should be specified explicitly like "x.y" (2.7, 3.6, 3.7)
+ * "3.x" or "3" are not supported
+ * because it could cause ambiguity when both PyPy version and Python version are not precise
+ */
+function validatePythonVersionFormatForPyPy(version) {
+    const re = /^\d+\.\d+$/;
+    return re.test(version);
+}
+exports.validatePythonVersionFormatForPyPy = validatePythonVersionFormatForPyPy;
 
 
 /***/ }),
diff --git a/src/find-pypy.ts b/src/find-pypy.ts
index b45f48f8..700ce9ee 100644
--- a/src/find-pypy.ts
+++ b/src/find-pypy.ts
@@ -4,7 +4,8 @@ import {
   IS_WINDOWS,
   validateVersion,
   getPyPyVersionFromPath,
-  readExactPyPyVersionFile
+  readExactPyPyVersionFile,
+  validatePythonVersionFormatForPyPy
 } from './utils';
 
 import * as semver from 'semver';
@@ -117,6 +118,12 @@ export function parsePyPyVersion(versionSpec: string): IPyPyVersionSpec {
     );
   }
 
+  if (!validatePythonVersionFormatForPyPy(pythonVersion)) {
+    throw new Error(
+      "Invalid format of Python version for PyPy. Python version should be specified in format 'x.y'. See README for examples and documentation."
+    );
+  }
+
   return {
     pypyVersion: pypyVersion,
     pythonVersion: pythonVersion
diff --git a/src/utils.ts b/src/utils.ts
index 845fe097..e96d5b23 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -80,3 +80,13 @@ export function writeExactPyPyVersionFile(
   const pypyFilePath = path.join(installDir, PYPY_VERSION_FILE);
   fs.writeFileSync(pypyFilePath, resolvedPyPyVersion);
 }
+
+/**
+ * Python version should be specified explicitly like "x.y" (2.7, 3.6, 3.7)
+ * "3.x" or "3" are not supported
+ * because it could cause ambiguity when both PyPy version and Python version are not precise
+ */
+export function validatePythonVersionFormatForPyPy(version: string) {
+  const re = /^\d+\.\d+$/;
+  return re.test(version);
+}