diff --git a/src/base.hpp b/src/base.hpp
index c808f08f5d9589d4a9bf26052d6b5f232cf6d690..281bd9bcff9909fd89b9a03159a63941873e4cd2 100644
--- a/src/base.hpp
+++ b/src/base.hpp
@@ -31,7 +31,7 @@ static const int message_buffer_length = 1024;
 static char debug_message_buffer[message_buffer_length];
 extern int myrank, nprocs;
 
-int MOD(int a, int n)
+inline int MOD(int a, int n)
 {
     return ((a%n) + n) % n;
 }