diff --git a/src/obidms.c b/src/obidms.c
index 871c2f3..c42e9ac 100755
--- a/src/obidms.c
+++ b/src/obidms.c
@@ -21,6 +21,7 @@
 #include <unistd.h>
 #include <libgen.h>   /* <EC> : Added July 28th 2017 to include basename */
 #include <sys/mman.h>
+#include <math.h>
 
 #include "obidms.h"
 #include "obierrno.h"
diff --git a/src/obiview.c b/src/obiview.c
index e294b3d..606c4bb 100755
--- a/src/obiview.c
+++ b/src/obiview.c
@@ -16,6 +16,7 @@
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <inttypes.h>
+#include <math.h>
 
 
 #include "obiview.h"