diff --git a/CHANGELOG.md b/CHANGELOG.md
index c45b93bc9..95e419b34 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -127,6 +127,13 @@
 * FilesystemAdapter::directoryExists to check for directory existence
 * FilesystemAdapter::fileExists to check for file existence
 
+## 2.4.4 - 2022-04-14
+
+### Fixed
+
+- [SFTP v2] Avoid type errors when public key is not retrieved (#1446)
+- [SFTP v3] Avoid type errors when public key is not retrieved (#1446)
+
 ## 2.4.3 - 2022-02-16
 
 ### Fixed
diff --git a/src/PhpseclibV2/SftpConnectionProvider.php b/src/PhpseclibV2/SftpConnectionProvider.php
index efd8ab5d1..c04a12ede 100644
--- a/src/PhpseclibV2/SftpConnectionProvider.php
+++ b/src/PhpseclibV2/SftpConnectionProvider.php
@@ -143,7 +143,12 @@ private function checkFingerprint(SFTP $connection): void
             return;
         }
 
-        $publicKey = $connection->getServerPublicHostKey() ?: 'no-public-key';
+        $publicKey = $connection->getServerPublicHostKey();
+
+        if ($publicKey === false) {
+            throw UnableToEstablishAuthenticityOfHost::becauseTheAuthenticityCantBeEstablished($this->host);
+        }
+
         $fingerprint = $this->getFingerprintFromPublicKey($publicKey);
 
         if (0 !== strcasecmp($this->hostFingerprint, $fingerprint)) {
diff --git a/src/PhpseclibV3/SftpConnectionProvider.php b/src/PhpseclibV3/SftpConnectionProvider.php
index 095085d21..ee843ba85 100644
--- a/src/PhpseclibV3/SftpConnectionProvider.php
+++ b/src/PhpseclibV3/SftpConnectionProvider.php
@@ -158,7 +158,12 @@ private function checkFingerprint(SFTP $connection): void
             return;
         }
 
-        $publicKey = $connection->getServerPublicHostKey() ?: 'no-public-key';
+        $publicKey = $connection->getServerPublicHostKey();
+
+        if ($publicKey === false) {
+            throw UnableToEstablishAuthenticityOfHost::becauseTheAuthenticityCantBeEstablished($this->host);
+        }
+
         $fingerprint = $this->getFingerprintFromPublicKey($publicKey);
 
         if (0 !== strcasecmp($this->hostFingerprint, $fingerprint)) {