diff --git a/engine/common/crc.c b/engine/common/crc.c
index b35958e26..6a4ce08e6 100644
--- a/engine/common/crc.c
+++ b/engine/common/crc.c
@@ -8,7 +8,7 @@ of the License, or (at your option) any later version.
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
 See the GNU General Public License for more details.
 
@@ -21,6 +21,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 #include "quakedef.h"
 #include "crc.h"
+#include <ctype.h>
 
 // this is a 16 bit, non-reflected CRC using the polynomial 0x1021
 // and the initial and final xor values shown below...  in other words, the