diff --git a/contrib/minizip/CMakeLists.txt b/contrib/minizip/CMakeLists.txt
index 775129f..5847c3c 100644
--- a/contrib/minizip/CMakeLists.txt
+++ b/contrib/minizip/CMakeLists.txt
@@ -129,6 +129,13 @@ set(MINIUNZIP_HDRS
     unzip.h
     zip.h)
 
+if(WITH_UNOFFICIAL_IOWIN32)
+    list(APPEND LIBMINIZIP_HDRS iowin32.h)
+    list(APPEND LIBMINIZIP_SRCS iowin32.c)
+    list(REMOVE_ITEM MINIZIP_SRCS $<$<BOOL:${WIN32}>:iowin32.c>)
+    list(REMOVE_ITEM MINIUNZIP_SRCS $<$<BOOL:${WIN32}>:iowin32.c>)
+endif()
+
 if(WIN32 OR CYGWIN)
     set(minizip_static_suffix "s")
     set(CMAKE_DEBUG_POSTFIX "d")