diff --git a/setup/wizardsteps.class.inc.php b/setup/wizardsteps.class.inc.php
index f8c947f85f..56fd97db03 100644
--- a/setup/wizardsteps.class.inc.php
+++ b/setup/wizardsteps.class.inc.php
@@ -1937,14 +1937,15 @@ protected function GetStepInfo($idx = null)
 	public function ComputeChoiceFlags(array $aChoice, string $sChoiceId, array $aSelectedComponents, bool $bAllDisabled, bool $bDisableUninstallCheck, bool $bUpgradeMode)
 	{
 		$oITopExtension = $this->oExtensionsMap->GetFromExtensionCode($aChoice['extension_code']);
+		//If the extension is missing from disk, it won't exist in the ExtensionsMap, thus returning null
 		$bCanBeUninstalled = isset($aChoice['uninstallable']) ? $aChoice['uninstallable'] === true || $aChoice['uninstallable'] === 'yes' : $oITopExtension->CanBeUninstalled();
 		$bSelected = isset($aSelectedComponents[$sChoiceId]) && ($aSelectedComponents[$sChoiceId] == $sChoiceId);
-		$bMandatory = (isset($aChoice['mandatory']) && $aChoice['mandatory']) || $bUpgradeMode && $oITopExtension->bInstalled && !$bCanBeUninstalled && !$bDisableUninstallCheck;
-
 		$bMissingFromDisk = isset($aChoice['missing']) && $aChoice['missing'] === true;
+
+		$bMandatory = (isset($aChoice['mandatory']) && $aChoice['mandatory']) || $bUpgradeMode && !$bMissingFromDisk && $oITopExtension->bInstalled && !$bCanBeUninstalled && !$bDisableUninstallCheck;
 		$bInstalled = $bMissingFromDisk || $oITopExtension->bInstalled;
 		$bDisabled = $bMandatory || $bAllDisabled || $bMissingFromDisk;
-		$bChecked = $bMandatory || $bSelected;
+		$bChecked = !$bMissingFromDisk && ($bMandatory || $bSelected);
 
 		if (isset($aChoice['sub_options'])) {
 			$aOptions = $aChoice['sub_options']['options'] ?? [];
diff --git a/tests/php-unit-tests/unitary-tests/setup/WizStepModulesChoiceTest.php b/tests/php-unit-tests/unitary-tests/setup/WizStepModulesChoiceTest.php
index 742cf00bc8..152284a1ca 100644
--- a/tests/php-unit-tests/unitary-tests/setup/WizStepModulesChoiceTest.php
+++ b/tests/php-unit-tests/unitary-tests/setup/WizStepModulesChoiceTest.php
@@ -67,6 +67,69 @@ public function ProviderComputeChoiceFlags()
 					'checked' => true,
 				],
 			],
+			'A missing extension should be disabled and unchecked' => [
+				'aExtensionsOnDiskOrDb' => [
+					'itop-ext1' => [
+						'installed' => true,
+					],
+				],
+				'aWizardStepDefinition' => [
+					'extension_code' => 'itop-ext1',
+					'mandatory' => false,
+					'missing' => true,
+					'uninstallable' => true,
+				],
+				'bCurrentSelected' => false,
+				'aExpectedFlags' => [
+					'uninstallable' => true,
+					'missing' => true,
+					'installed' => true,
+					'disabled' => true,
+					'checked' => false,
+				],
+			],
+			'A missing extension should always be disabled and unchecked, even when mandatory' => [
+				'aExtensionsOnDiskOrDb' => [
+					'itop-ext1' => [
+						'installed' => true,
+					],
+				],
+				'aWizardStepDefinition' => [
+					'extension_code' => 'itop-ext1',
+					'mandatory' => true,
+					'missing' => true,
+					'uninstallable' => true,
+				],
+				'bCurrentSelected' => false,
+				'aExpectedFlags' => [
+					'uninstallable' => true,
+					'missing' => true,
+					'installed' => true,
+					'disabled' => true,
+					'checked' => false,
+				],
+			],
+			'A missing extension should always be disabled and unchecked, even when non-uninstallable' => [
+				'aExtensionsOnDiskOrDb' => [
+					'itop-ext1' => [
+						'installed' => true,
+					],
+				],
+				'aWizardStepDefinition' => [
+					'extension_code' => 'itop-ext1',
+					'mandatory' => true,
+					'missing' => true,
+					'uninstallable' => false,
+				],
+				'bCurrentSelected' => false,
+				'aExpectedFlags' => [
+					'uninstallable' => false,
+					'missing' => true,
+					'installed' => true,
+					'disabled' => true,
+					'checked' => false,
+				],
+			],
 			'An installed but not selected extension should not be checked and be enabled' => [
 				'aExtensionsOnDiskOrDb' => [
 					'itop-ext1' => [