diff --git a/lib/private/Config.php b/lib/private/Config.php
index 278c6816e70ea..d69a9837e7543 100644
--- a/lib/private/Config.php
+++ b/lib/private/Config.php
@@ -80,7 +80,7 @@ public function __construct($configDir, $fileName = 'config.php') {
 	 * @return array an array of key names
 	 */
 	public function getKeys() {
-		return array_keys($this->cache);
+		return array_merge(array_keys($this->cache), array_keys($this->envCache));
 	}
 
 	/**
@@ -95,9 +95,8 @@ public function getKeys() {
 	 * @return mixed the value or $default
 	 */
 	public function getValue($key, $default = null) {
-		$envKey = self::ENV_PREFIX . $key;
-		if (isset($this->envCache[$envKey])) {
-			return $this->envCache[$envKey];
+		if (isset($this->envCache[$key])) {
+			return $this->envCache[$key];
 		}
 
 		if (isset($this->cache[$key])) {
@@ -257,7 +256,16 @@ private function readData() {
 			}
 		}
 
-		$this->envCache = getenv();
+		// grab any "NC_" environment variables
+		$envRaw = getenv();
+		// only save environment variables prefixed with "NC_" in the cache
+		$envPrefixLen = strlen(self::ENV_PREFIX);
+		foreach ($envRaw as $rawEnvKey => $rawEnvValue) {
+			if (str_starts_with($rawEnvKey, self::ENV_PREFIX)) {
+				$realKey = substr($rawEnvKey, $envPrefixLen);
+				$this->envCache[$realKey] = $rawEnvValue;
+			}
+		}
 	}
 
 	/**
diff --git a/tests/lib/ConfigTest.php b/tests/lib/ConfigTest.php
index 7c289472abd4e..22860f6f130c8 100644
--- a/tests/lib/ConfigTest.php
+++ b/tests/lib/ConfigTest.php
@@ -42,6 +42,13 @@ public function testGetKeys() {
 		$this->assertSame($expectedConfig, $this->getConfig()->getKeys());
 	}
 
+	public function testGetKeysReturnsEnvironmentKeysIfSet() {
+		$expectedConfig = ['foo', 'beers', 'alcohol_free', 'taste'];
+		putenv('NC_taste=great');
+		$this->assertSame($expectedConfig, $this->getConfig()->getKeys());
+		putenv('NC_taste');
+	}
+
 	public function testGetValue() {
 		$config = $this->getConfig();
 		$this->assertSame('bar', $config->getValue('foo'));