diff --git a/lifeclock-v1/constants.h b/lifeclock-v1/constants.h
index a18a8da..53bee41 100644
--- a/lifeclock-v1/constants.h
+++ b/lifeclock-v1/constants.h
@@ -1,6 +1,8 @@
 #ifndef CONSTANTS_H
 #define CONSTANTS_H
 
+#define DESIRED_LIFESPAN 100 // years
+
 #define LED_PIN 6
 #define SET_LED_PIN 42
 #define DATE_LED_PIN 43
diff --git a/lifeclock-v1/functions.cpp b/lifeclock-v1/functions.cpp
index 550cb22..41c7763 100644
--- a/lifeclock-v1/functions.cpp
+++ b/lifeclock-v1/functions.cpp
@@ -250,7 +250,7 @@ void setTime() {
 unsigned long getSecondsTillDeath() {
   tm2.Day = birthDate.date;
   tm2.Month = birthDate.month;
-  tm2.Year = birthDate.year + 80 - 1970;
+  tm2.Year = birthDate.year + DESIRED_LIFESPAN - 1970;
   tm2.Hour = tm2.Minute = tm2.Second = 0;
   time_t t1 = makeTime(tm);
   time_t t2 = makeTime(tm2);