diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -2969,6 +2969,19 @@ bool AfterLoadGame()
 #endif
 	}
 
+	if (IsSavegameVersionBefore(198)) {
+		/* Convert towns growth_rate and grow_counter to ticks */
+		Town *t;
+		FOR_ALL_TOWNS(t) {
+			/* 0x8000 = TOWN_GROWTH_RATE_CUSTOM previously */
+			if (t->growth_rate & 0x8000) SetBit(t->flags, TOWN_CUSTOM_GROWTH);
+			if (t->growth_rate != TOWN_GROWTH_RATE_NONE) {
+				t->growth_rate = TownTicksToGameTicks(t->growth_rate & ~0x8000);
+			}
+			/* Add t->index % TOWN_GROWTH_TICKS to spread growth across ticks. */
+			t->grow_counter = TownTicksToGameTicks(t->grow_counter) + t->index % TOWN_GROWTH_TICKS;
+		}
+	}
 
 	/* Station acceptance is some kind of cache */
 	if (IsSavegameVersionBefore(127)) {