diff --git a/code/Q3BSPZipArchive.cpp b/code/Q3BSPZipArchive.cpp
index 86c966d8e..1c8b18ad3 100644
--- a/code/Q3BSPZipArchive.cpp
+++ b/code/Q3BSPZipArchive.cpp
@@ -43,6 +43,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "Q3BSPZipArchive.h"
 #include <cassert>
+#include <cstdlib>
 #include <assimp/ai_assert.h>
 
 namespace Assimp {