diff --git a/apps/dav/lib/Connector/Sabre/MtimeSanitizer.php b/apps/dav/lib/Connector/Sabre/MtimeSanitizer.php
index e18ef58149a2b..48d210ebb1bfa 100644
--- a/apps/dav/lib/Connector/Sabre/MtimeSanitizer.php
+++ b/apps/dav/lib/Connector/Sabre/MtimeSanitizer.php
@@ -14,12 +14,22 @@ public static function sanitizeMtime(string $mtimeFromRequest): int {
 		// ensures that strings with hexadecimal notations fail too in PHP 5.X.
 		$isHexadecimal = preg_match('/^\s*0[xX]/', $mtimeFromRequest);
 		if ($isHexadecimal || !is_numeric($mtimeFromRequest)) {
-			throw new \InvalidArgumentException('X-OC-MTime header must be an integer (unix timestamp).');
+			throw new \InvalidArgumentException(
+				sprintf(
+					'X-OC-MTime header must be a valid integer (unix timestamp), got "%s".',
+					$mtimeFromRequest
+				)
+			);
 		}
 
 		// Prevent writing invalid mtime (timezone-proof)
 		if ((int)$mtimeFromRequest <= 24 * 60 * 60) {
-			throw new \InvalidArgumentException('X-OC-MTime header must be a valid positive integer');
+			throw new \InvalidArgumentException(
+				sprintf(
+					'X-OC-MTime header must be a valid positive unix timestamp greater than one day, got "%s".',
+					$mtimeFromRequest
+				)
+			);
 		}
 
 		return (int)$mtimeFromRequest;