diff --git a/pycardium/mphalport.c b/pycardium/mphalport.c
index 038fb5dfaaa4cb6c3a30e09801a69ed7d15d145b..a45a8776365477251ee801ef8ca06ecde131293e 100644
--- a/pycardium/mphalport.c
+++ b/pycardium/mphalport.c
@@ -26,7 +26,7 @@
 
 /* Target systick interval is 1 second */
 #define SYSTICK_INTERVAL_US                                                    \
-	(SYSTICK_INTERVAL_US_MIN * (1000000 / SYSTICK_INTERVAL_US_MIN))
+	(SYSTICK_INTERVAL_US_MIN * (1000000LL / SYSTICK_INTERVAL_US_MIN))
 
 /*
  * Copied from core_cm4.h and modified to select the