diff --git a/Sources/GZip/GzipArchive.swift b/Sources/GZip/GzipArchive.swift
index 7a840402..0cafe099 100644
--- a/Sources/GZip/GzipArchive.swift
+++ b/Sources/GZip/GzipArchive.swift
@@ -77,8 +77,9 @@ public class GzipArchive: Archive {
     }
 
     private static func processMember(_ bitReader: LsbBitReader) throws -> Member {
-        // Valid GZip archive must contain at least 18 bytes of data (10 for header and 8 for checksums).
-        guard bitReader.bitsLeft >= 18 * 8
+        // Valid GZip archive must contain at least 20 bytes of data (10 for the header, 2 for an empty Deflate block,
+        // and 8 for checksums).
+        guard bitReader.bitsLeft >= 20 * 8
             else { throw GzipError.wrongMagic }
 
         let header = try GzipHeader(bitReader)