diff --git a/lib/Service/SmimeService.php b/lib/Service/SmimeService.php
index 5276e2682d..870d1aa79f 100644
--- a/lib/Service/SmimeService.php
+++ b/lib/Service/SmimeService.php
@@ -84,7 +84,7 @@ public function verifyMessage(string $message): bool {
 		// smime/pkcs7 module. Unfortunately, it is only supported since php 8.
 		// Ref https://www.php.net/manual/en/function.openssl-cms-verify.php
 
-		$messageTemp = $this->tempManager->getTemporaryFile();
+		$messageTemp = $this->getTemporaryFileOrThrow();
 		$messageTempHandle = fopen($messageTemp, 'wb');
 		fwrite($messageTempHandle, $message);
 		fclose($messageTempHandle);
@@ -122,8 +122,8 @@ public function extractSignedContent(string $message): string {
 		// smime/pkcs7 module. Unfortunately, it is only supported since php 8.
 		// Ref https://www.php.net/manual/en/function.openssl-cms-verify.php
 
-		$verifiedContentTemp = $this->tempManager->getTemporaryFile();
-		$messageTemp = $this->tempManager->getTemporaryFile();
+		$verifiedContentTemp = $this->getTemporaryFileOrThrow();
+		$messageTemp = $this->getTemporaryFileOrThrow();
 		$messageTempHandle = fopen($messageTemp, 'wb');
 		fwrite($messageTempHandle, $message);
 		fclose($messageTempHandle);
@@ -182,7 +182,7 @@ public function parseCertificate(string $certificate): SmimeCertificateInfo {
 			}
 		}
 
-		$decryptedCertificateFile = $this->tempManager->getTemporaryFile();
+		$decryptedCertificateFile = $this->getTemporaryFileOrThrow();
 		file_put_contents($decryptedCertificateFile, $certificate);
 
 		$caBundle = [$this->certificateManager->getAbsoluteBundlePath()];
@@ -379,11 +379,11 @@ public function signMimePart(Horde_Mime_Part  $part,
 			);
 		}
 
-		$decryptedCertificateFile = $this->tempManager->getTemporaryFile();
+		$decryptedCertificateFile = $this->getTemporaryFileOrThrow();
 		file_put_contents($decryptedCertificateFile, $decryptedCertificate);
 
-		$inPath = $this->tempManager->getTemporaryFile();
-		$outPath = $this->tempManager->getTemporaryFile();
+		$inPath = $this->getTemporaryFileOrThrow();
+		$outPath = $this->getTemporaryFileOrThrow();
 		file_put_contents($inPath, $part->toString([
 			'canonical' => true,
 			'headers' => true,
@@ -441,8 +441,8 @@ public function decryptMimePartText(string $mimePartText,
 			);
 		}
 
-		$inPath = $this->tempManager->getTemporaryFile();
-		$outPath = $this->tempManager->getTemporaryFile();
+		$inPath = $this->getTemporaryFileOrThrow();
+		$outPath = $this->getTemporaryFileOrThrow();
 		file_put_contents($inPath, $mimePartText);
 		if (!openssl_pkcs7_decrypt($inPath, $outPath, $decryptedCertificate, $decryptedKey)) {
 			throw new SmimeDecryptException('Failed to decrypt MIME part text');
@@ -597,8 +597,8 @@ public function encryptMimePart(Horde_Mime_Part  $part, array $certificates): Ho
 			throw new ServiceException('Failed to decrypt certificate: ' . $e->getMessage(), 0, $e);
 		}
 
-		$inPath = $this->tempManager->getTemporaryFile();
-		$outPath = $this->tempManager->getTemporaryFile();
+		$inPath = $this->getTemporaryFileOrThrow();
+		$outPath = $this->getTemporaryFileOrThrow();
 		file_put_contents($inPath, $part->toString([
 			'canonical' => true,
 			'headers' => true,
@@ -626,4 +626,18 @@ public function encryptMimePart(Horde_Mime_Part  $part, array $certificates): Ho
 
 		return $parsedPart;
 	}
+
+	/**
+	 * Create a temporary file and return the path or throw if it could not be created.
+	 *
+	 * @throws ServiceException If the temporary file could not be created
+	 */
+	private function getTemporaryFileOrThrow(): string {
+		$file = $this->tempManager->getTemporaryFile();
+		if ($file === false) {
+			throw new ServiceException('Failed to create temporary file');
+		}
+
+		return $file;
+	}
 }