diff --git a/Userland/Libraries/LibCompress/Zlib.h b/Userland/Libraries/LibCompress/Zlib.h
index c0fb33f267..148ecca809 100644
--- a/Userland/Libraries/LibCompress/Zlib.h
+++ b/Userland/Libraries/LibCompress/Zlib.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
+#include <AK/Optional.h>
 #include <AK/Span.h>
 #include <AK/Types.h>