diff --git a/contrib/libzip/premake5.lua b/contrib/libzip/premake5.lua
index c35592a51..f0b91b562 100644
--- a/contrib/libzip/premake5.lua
+++ b/contrib/libzip/premake5.lua
@@ -13,6 +13,7 @@ project "zip-lib"
 
 	filter "system:linux or bsd or solaris or haiku"
 		defines { "HAVE_SSIZE_T_LIBZIP", "HAVE_CONFIG_H" }
+		forceincludes { "unistd.h" }
 
 	filter "system:windows"
 		defines { "_WINDOWS" }