diff --git a/api/mraa/common.hpp b/api/mraa/common.hpp
index 1841620..6c5552c 100644
--- a/api/mraa/common.hpp
+++ b/api/mraa/common.hpp
@@ -262,7 +262,8 @@ getSubPlatformId(int pin_or_bus_index)
  *
  * @return int pin or bus index
  */
-int getSubPlatformIndex(int pin_or_bus_id)
+inline int
+getSubPlatformIndex(int pin_or_bus_id)
 {
     return mraa_get_sub_platform_index(pin_or_bus_id);
 }