diff --git a/Sources/LZ77/Deflator/LZ77.DeflatorBuffers.Stream.swift b/Sources/LZ77/Deflator/LZ77.DeflatorBuffers.Stream.swift
index 3dddf6cb..cfae46a1 100644
--- a/Sources/LZ77/Deflator/LZ77.DeflatorBuffers.Stream.swift
+++ b/Sources/LZ77/Deflator/LZ77.DeflatorBuffers.Stream.swift
@@ -436,7 +436,7 @@ extension LZ77.DeflatorBuffers.Stream
     }
 
     /// Emits a dynamic (type = 2) DEFLATE block.
-    mutating
+    private mutating
     func writeBlock(final:Bool = false)
     {
         let tree:
diff --git a/Sources/LZ77/Deflator/LZ77.DeflatorBuffers.swift b/Sources/LZ77/Deflator/LZ77.DeflatorBuffers.swift
index 9ab0cd0d..c5061cde 100644
--- a/Sources/LZ77/Deflator/LZ77.DeflatorBuffers.swift
+++ b/Sources/LZ77/Deflator/LZ77.DeflatorBuffers.swift
@@ -80,7 +80,8 @@ extension LZ77.DeflatorBuffers<LZ77.Format>
 
         self.stream.compressBlocks(final: last)
 
-        guard case .zlib = self.format
+        guard last,
+        case .zlib = self.format
         else
         {
             return
@@ -123,6 +124,12 @@ extension LZ77.DeflatorBuffers<Gzip.Format>
 
         self.stream.compressBlocks(final: last)
 
+        guard last
+        else
+        {
+            return
+        }
+
         let checksum:UInt32 = self.stream.input.checksum()
         let bytes:UInt32 = self.stream.input.integral.bytes
         self.stream.writeLittleEndianUInt32(checksum)