diff --git a/sources/Service/Router/Router.php b/sources/Service/Router/Router.php
index 1566a4c90..8ef5d015f 100644
--- a/sources/Service/Router/Router.php
+++ b/sources/Service/Router/Router.php
@@ -138,12 +138,15 @@ class Router
 	{
 		$aRoutes = [];
 		$bUseCache = false === utils::IsDevelopmentEnvironment();
+		$bMustWriteCache = false;
 		$sCacheFilePath = $this->GetCacheFileAbsPath();
 
 		// Try to read from cache
 		if ($bUseCache) {
 			if (is_file($sCacheFilePath)) {
 				$aRoutes = include $sCacheFilePath;
+			} else {
+				$bMustWriteCache = true;
 			}
 		}
 
@@ -180,11 +183,11 @@ class Router
 			}
 		}
 
-		// Save to cache
-		if ($bUseCache) {
+		// Save to cache if it doesn't exist already
+		if ($bMustWriteCache) {
 			$sCacheContent = "<?php\n\nreturn ".var_export($aRoutes, true).";";
 			SetupUtils::builddir(dirname($sCacheFilePath));
-			file_put_contents($sCacheFilePath, $sCacheContent);
+			file_put_contents($sCacheFilePath, $sCacheContent, LOCK_EX);
 		}
 
 		return $aRoutes;
diff --git a/tests/php-unit-tests/unitary-tests/sources/Service/Router/RouterTest.php b/tests/php-unit-tests/unitary-tests/sources/Service/Router/RouterTest.php
index f110c6b53..5b7deb4a3 100644
--- a/tests/php-unit-tests/unitary-tests/sources/Service/Router/RouterTest.php
+++ b/tests/php-unit-tests/unitary-tests/sources/Service/Router/RouterTest.php
@@ -20,6 +20,16 @@ use utils;
  */
 class RouterTest extends ItopTestCase
 {
+	/**
+	 * @inheritDoc
+	 */
+	protected function setUp(): void
+	{
+		parent::setUp();
+
+		$this->RequireOnceItopFile('setup/setuputils.class.inc.php');
+	}
+
 	/**
 	 * @covers \Combodo\iTop\Service\Router\Router::GenerateUrl
 	 * @dataProvider GenerateUrlProvider
@@ -169,6 +179,56 @@ class RouterTest extends ItopTestCase
 		$this->assertEquals($bShouldBePresent, $bIsPresent, "Route '$sRoute' was not expected amongst the available routes.");
 	}
 
+	/**
+	 * @covers \Combodo\iTop\Service\Router\Router::GetRoutes
+	 * @return void
+	 *
+	 * @details Covers the cache generation within the GetRoutes method
+	 * @since N°6618
+	 */
+	public function testGetRoutesCacheGeneration(): void
+	{
+		$oRouter = Router::GetInstance();
+		$sRoutesCacheFilePath = $this->InvokeNonPublicMethod(Router::class, 'GetCacheFileAbsPath', $oRouter, []);
+
+		// Developer mode must be disabled for the routes cache to be used
+		$oConf = utils::GetConfig();
+		$mDeveloperModePreviousValue = $oConf->Get('developer_mode.enabled');
+		$oConf->Set('developer_mode.enabled', false);
+
+		// Generate cache for first time
+		$this->InvokeNonPublicMethod(Router::class, 'GetRoutes', $oRouter, []);
+
+		// Check that file exists and retrieve modification timestamp
+		if (false === is_file($sRoutesCacheFilePath)) {
+			$this->fail("Cache file was not generated ($sRoutesCacheFilePath)");
+		}
+
+		clearstatcache();
+		$iFirstModificationTimestamp = filemtime($sRoutesCacheFilePath);
+		$this->debug("Initial timestamp: $iFirstModificationTimestamp");
+
+		// Wait for just 1s to ensure timestamps would be different is the file is re-generated
+		sleep(1);
+
+		// Call GetRoutes() again to see if cache gets re-generated or not
+		$this->InvokeNonPublicMethod(Router::class, 'GetRoutes', $oRouter, []);
+
+		// Check that file still exists and that modification timestamp has not changed
+		if (false === is_file($sRoutesCacheFilePath)) {
+			$this->fail("Cache file is no longer present, that should not happen! ($sRoutesCacheFilePath)");
+		}
+
+		clearstatcache();
+		$iSecondModificationTimestamp = filemtime($sRoutesCacheFilePath);
+		$this->debug("Second timestamp: $iSecondModificationTimestamp");
+
+		$this->assertSame($iFirstModificationTimestamp, $iSecondModificationTimestamp, "Cache file timestamp changed, seems like cache is not working and was re-generated when it should not!");
+
+		// Restore previous value for following tests
+		$oConf->Set('developer_mode.enabled', $mDeveloperModePreviousValue);
+	}
+
 	public function GetRoutesProvider(): array
 	{
 		return [