diff --git a/src/races/dragons.c b/src/races/dragons.c
index ec16f78dc..5ab877c40 100644
--- a/src/races/dragons.c
+++ b/src/races/dragons.c
@@ -27,26 +27,26 @@ static int age_chance(int a, int b, int p) {
     return (r < 0) ? 0 : r;
 }
 
-#define DRAGONAGE                   27
-#define WYRMAGE                     68
+#define DRAGONAGE 27
+#define WYRMAGE 68
+
+static void evolve_dragon(unit * u, const struct race *rc) {
+    scale_number(u, 1);
+    u_setrace(u, rc);
+    u->irace = NULL;
+    u->hp = unit_max_hp(u);
+}
 
 void age_firedragon(unit * u)
 {
     if (u->number > 0 && rng_int() % 100 < age_chance(u->age, DRAGONAGE, 1)) {
-        double q = (double)u->hp / (double)(unit_max_hp(u) * u->number);
-        u_setrace(u, get_race(RC_DRAGON));
-        u->irace = NULL;
-        scale_number(u, 1);
-        u->hp = (int)(unit_max_hp(u) * u->number * q);
+        evolve_dragon(u, get_race(RC_DRAGON));
     }
 }
 
 void age_dragon(unit * u)
 {
     if (u->number > 0 && rng_int() % 100 < age_chance(u->age, WYRMAGE, 1)) {
-        double q = (double)u->hp / (double)(unit_max_hp(u) * u->number);
-        u_setrace(u, get_race(RC_WYRM));
-        u->irace = NULL;
-        u->hp = (int)(unit_max_hp(u) * u->number * q);
+        evolve_dragon(u, get_race(RC_WYRM));
     }
 }