diff --git a/contrib/libzip/premake5.lua b/contrib/libzip/premake5.lua
index 1532d5182f..c35592a516 100644
--- a/contrib/libzip/premake5.lua
+++ b/contrib/libzip/premake5.lua
@@ -21,3 +21,4 @@ project "zip-lib"
 
 	filter "system:macosx"
 		defines { "HAVE_SSIZE_T_LIBZIP" }
+		forceincludes { "unistd.h" }