diff --git a/include/tools.h b/include/tools.h
index 4c73991..f83ba09 100644
--- a/include/tools.h
+++ b/include/tools.h
@@ -5,10 +5,10 @@
 
 #include "globals.h"
 
-inline int mod_abs (int a, int b) {
+static inline int mod_abs (int a, int b) {
   return ((a % b) + b) % b;
 }
-inline int div_floor (int a, int b) {
+static inline int div_floor (int a, int b) {
   return a % b < 0 ? (a - b) / b : a / b;
 }