diff --git a/bukkit-helper-118/src/main/java/org/dynmap/bukkit/helper/v118/MapChunkCache118.java b/bukkit-helper-118/src/main/java/org/dynmap/bukkit/helper/v118/MapChunkCache118.java
index 6dc7fbcc..242aba25 100644
--- a/bukkit-helper-118/src/main/java/org/dynmap/bukkit/helper/v118/MapChunkCache118.java
+++ b/bukkit-helper-118/src/main/java/org/dynmap/bukkit/helper/v118/MapChunkCache118.java
@@ -223,7 +223,7 @@ public class MapChunkCache118 extends GenericMapChunkCache {
             }
 			else {	// Else, apply legacy biomes
 				if (old3d != null) {
-					BiomeMap m[] = old3d.get(secnum);
+					BiomeMap m[] = old3d.get((secnum > 0) ? ((secnum < old3d.size()) ? secnum : old3d.size()-1) : 0);
 					if (m != null) {
 		                for (int j = 0; j < 64; j++) {
 		                    sbld.xyzBiome(j & 0x3, (j & 0x30) >> 4, (j & 0xC) >> 2, m[j]);
diff --git a/fabric-1.18/src/main/java/org/dynmap/fabric_1_18/FabricMapChunkCache.java b/fabric-1.18/src/main/java/org/dynmap/fabric_1_18/FabricMapChunkCache.java
index 038fb910..3a649719 100644
--- a/fabric-1.18/src/main/java/org/dynmap/fabric_1_18/FabricMapChunkCache.java
+++ b/fabric-1.18/src/main/java/org/dynmap/fabric_1_18/FabricMapChunkCache.java
@@ -265,7 +265,7 @@ public class FabricMapChunkCache extends GenericMapChunkCache {
             }
 			else {	// Else, apply legacy biomes
 				if (old3d != null) {
-					BiomeMap m[] = old3d.get(secnum);
+					BiomeMap m[] = old3d.get((secnum > 0) ? ((secnum < old3d.size()) ? secnum : old3d.size()-1) : 0);
 					if (m != null) {
 		                for (int j = 0; j < 64; j++) {
 		                    sbld.xyzBiome(j & 0x3, (j & 0x30) >> 4, (j & 0xC) >> 2, m[j]);
diff --git a/forge-1.18/src/main/java/org/dynmap/forge_1_18/ForgeMapChunkCache.java b/forge-1.18/src/main/java/org/dynmap/forge_1_18/ForgeMapChunkCache.java
index 64a9a877..849c63f0 100644
--- a/forge-1.18/src/main/java/org/dynmap/forge_1_18/ForgeMapChunkCache.java
+++ b/forge-1.18/src/main/java/org/dynmap/forge_1_18/ForgeMapChunkCache.java
@@ -230,7 +230,7 @@ public class ForgeMapChunkCache extends GenericMapChunkCache {
             }
 			else {	// Else, apply legacy biomes
 				if (old3d != null) {
-					BiomeMap m[] = old3d.get(secnum);
+					BiomeMap m[] = old3d.get((secnum > 0) ? ((secnum < old3d.size()) ? secnum : old3d.size()-1) : 0);
 					if (m != null) {
 		                for (int j = 0; j < 64; j++) {
 		                    sbld.xyzBiome(j & 0x3, (j & 0x30) >> 4, (j & 0xC) >> 2, m[j]);