diff --git a/codec/image_to_j2k.c b/codec/image_to_j2k.c
index 89cbc3cc..bde18543 100644
--- a/codec/image_to_j2k.c
+++ b/codec/image_to_j2k.c
@@ -31,6 +31,7 @@
  */
 #include <stdio.h>
 #include <string.h>
+#include <strings.h> /* strncasecmp */
 #include <stdlib.h>
 #include <math.h>