diff --git a/buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts b/buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
index e61b437760..622c2d7f9b 100644
--- a/buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
+++ b/buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
@@ -38,6 +38,12 @@ java {
 repositories {
     mavenCentral()
 
+    mavenLocal {
+        content {
+            includeModule("org.squiddev", "Cobalt")
+        }
+    }
+
     val mainMaven = maven("https://squiddev.cc/maven") {
         name = "SquidDev"
         content {
@@ -57,7 +63,6 @@ repositories {
 
         filter {
             includeGroup("cc.tweaked")
-            includeModule("org.squiddev", "Cobalt")
             // Things we mirror
             includeGroup("commoble.morered")
             includeGroup("dev.architectury")
diff --git a/gradle.properties b/gradle.properties
index dfa227cb4c..23fbfbebe6 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -10,7 +10,7 @@ kotlin.jvm.target.validation.mode=error
 
 # Mod properties
 isUnstable=false
-modVersion=1.108.3
+modVersion=1.109.0-SNAPSHOT
 
 # Minecraft properties: We want to configure this here so we can read it in settings.gradle
 mcVersion=1.20.1
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index db44bf33b4..d633bd1633 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -19,8 +19,8 @@ parchmentMc = "1.20.1"
 asm = "9.5"
 autoService = "1.1.1"
 checkerFramework = "3.32.0"
-cobalt = "0.7.3"
-cobalt-next = "0.7.4" # Not a real version, used to constrain the version we accept.
+cobalt = "0.8.0-SNAPSHOT"
+cobalt-next = "0.8.1" # Not a real version, used to constrain the version we accept.
 fastutil = "8.5.9"
 guava = "31.1-jre"
 jetbrainsAnnotations = "24.0.1"
diff --git a/projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java b/projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java
index 3510c89560..ade0cf4d6a 100644
--- a/projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java
+++ b/projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java
@@ -73,20 +73,20 @@ public CobaltLuaMachine(MachineEnvironment environment, InputStream bios) throws
             .build();
 
         // Set up our global table.
-        var globals = state.getMainThread().getfenv();
-        CoreLibraries.debugGlobals(state);
-        Bit32Lib.add(state, globals);
-        globals.rawset("_HOST", ValueFactory.valueOf(environment.hostString()));
-        globals.rawset("_CC_DEFAULT_SETTINGS", ValueFactory.valueOf(CoreConfig.defaultComputerSettings));
+        try {
+            var globals = state.globals();
+            CoreLibraries.debugGlobals(state);
+            Bit32Lib.add(state, globals);
+            globals.rawset("_HOST", ValueFactory.valueOf(environment.hostString()));
+            globals.rawset("_CC_DEFAULT_SETTINGS", ValueFactory.valueOf(CoreConfig.defaultComputerSettings));
 
-        // Add default APIs
-        for (var api : environment.apis()) addAPI(globals, api);
+            // Add default APIs
+            for (var api : environment.apis()) addAPI(globals, api);
 
-        // And load the BIOS
-        try {
+            // And load the BIOS
             var value = LoadState.load(state, bios, "@bios.lua", globals);
-            mainRoutine = new LuaThread(state, value, globals);
-        } catch (CompileException e) {
+            mainRoutine = new LuaThread(state, value);
+        } catch (LuaError | CompileException e) {
             throw new MachineException(Nullability.assertNonNull(e.getMessage()));
         }
 
@@ -171,7 +171,7 @@ private LuaTable wrapLuaObject(Object object) {
         return found ? table : null;
     }
 
-    private LuaValue toValue(@Nullable Object object, @Nullable IdentityHashMap<Object, LuaValue> values) {
+    private LuaValue toValue(@Nullable Object object, @Nullable IdentityHashMap<Object, LuaValue> values) throws LuaError {
         if (object == null) return Constants.NIL;
         if (object instanceof Number num) return ValueFactory.valueOf(num.doubleValue());
         if (object instanceof Boolean bool) return ValueFactory.valueOf(bool);
@@ -235,7 +235,7 @@ private LuaValue toValue(@Nullable Object object, @Nullable IdentityHashMap<Obje
         return Constants.NIL;
     }
 
-    Varargs toValues(@Nullable Object[] objects) {
+    Varargs toValues(@Nullable Object[] objects) throws LuaError {
         if (objects == null || objects.length == 0) return Constants.NONE;
         if (objects.length == 1) return toValue(objects[0], null);
 
diff --git a/projects/core/src/main/resources/data/computercraft/lua/bios.lua b/projects/core/src/main/resources/data/computercraft/lua/bios.lua
index 2f3493dd77..2ba511e824 100644
--- a/projects/core/src/main/resources/data/computercraft/lua/bios.lua
+++ b/projects/core/src/main/resources/data/computercraft/lua/bios.lua
@@ -18,33 +18,6 @@ do
     expect = f().expect
 end
 
-if _VERSION == "Lua 5.1" then
-    -- If we're on Lua 5.1, install parts of the Lua 5.2/5.3 API so that programs can be written against it
-    local nativeload = load
-
-    function load(x, name, mode, env)
-        expect(1, x, "function", "string")
-        expect(2, name, "string", "nil")
-        expect(3, mode, "string", "nil")
-        expect(4, env, "table", "nil")
-
-        local ok, p1, p2 = pcall(function()
-            local result, err = nativeload(x, name, mode, env)
-            if result and env then
-                env._ENV = env
-            end
-            return result, err
-        end)
-        if ok then
-            return p1, p2
-        else
-            error(p1, 2)
-        end
-    end
-
-    loadstring = function(string, chunkname) return nativeload(string, chunkname) end
-end
-
 -- Inject a stub for the old bit library
 _G.bit = {
     bnot = bit32.bnot,
@@ -58,7 +31,7 @@ _G.bit = {
 
 -- Install lua parts of the os api
 function os.version()
-    return "CraftOS 1.8"
+    return "CraftOS 1.9"
 end
 
 function os.pullEventRaw(sFilter)
diff --git a/projects/core/src/main/resources/data/computercraft/lua/rom/help/changelog.md b/projects/core/src/main/resources/data/computercraft/lua/rom/help/changelog.md
index d30b8f5598..563dda95c5 100644
--- a/projects/core/src/main/resources/data/computercraft/lua/rom/help/changelog.md
+++ b/projects/core/src/main/resources/data/computercraft/lua/rom/help/changelog.md
@@ -1,3 +1,7 @@
+# New features in CC: Tweaked 1.109.0-SNAPSHOT
+
+Mistakes.
+
 # New features in CC: Tweaked 1.108.3
 
 Several bug fixes:
diff --git a/projects/core/src/main/resources/data/computercraft/lua/rom/help/whatsnew.md b/projects/core/src/main/resources/data/computercraft/lua/rom/help/whatsnew.md
index ccb06c6c1d..9ad91ad31a 100644
--- a/projects/core/src/main/resources/data/computercraft/lua/rom/help/whatsnew.md
+++ b/projects/core/src/main/resources/data/computercraft/lua/rom/help/whatsnew.md
@@ -1,6 +1,5 @@
-New features in CC: Tweaked 1.108.3
+New features in CC: Tweaked 1.109.0-SNAPSHOT
 
-Several bug fixes:
-* Fix disconnect when joining a dedicated server.
+Mistakes.
 
 Type "help changelog" to see the full version history.
diff --git a/projects/core/src/test/java/dan200/computercraft/core/LuaCoverage.java b/projects/core/src/test/java/dan200/computercraft/core/LuaCoverage.java
index 8da47d0a20..e7306c7807 100644
--- a/projects/core/src/test/java/dan200/computercraft/core/LuaCoverage.java
+++ b/projects/core/src/test/java/dan200/computercraft/core/LuaCoverage.java
@@ -10,6 +10,8 @@
 import it.unimi.dsi.fastutil.ints.IntSet;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.squiddev.cobalt.LuaError;
+import org.squiddev.cobalt.LuaState;
 import org.squiddev.cobalt.Prototype;
 import org.squiddev.cobalt.compiler.CompileException;
 import org.squiddev.cobalt.compiler.LuaC;
@@ -108,9 +110,9 @@ private static IntSet getActiveLines(File file) throws IOException {
         Queue<Prototype> queue = new ArrayDeque<>();
 
         try (InputStream stream = new FileInputStream(file)) {
-            var proto = LuaC.compile(stream, "@" + file.getPath());
+            var proto = LuaC.compile(new LuaState(), stream, "@" + file.getPath());
             queue.add(proto);
-        } catch (CompileException e) {
+        } catch (LuaError | CompileException e) {
             throw new IllegalStateException("Cannot compile", e);
         }
 
diff --git a/projects/core/src/test/java/dan200/computercraft/core/lua/VarargArgumentsTest.java b/projects/core/src/test/java/dan200/computercraft/core/lua/VarargArgumentsTest.java
index 97a6aa36c2..5c4da7722f 100644
--- a/projects/core/src/test/java/dan200/computercraft/core/lua/VarargArgumentsTest.java
+++ b/projects/core/src/test/java/dan200/computercraft/core/lua/VarargArgumentsTest.java
@@ -7,6 +7,7 @@
 import dan200.computercraft.api.lua.LuaException;
 import org.junit.jupiter.api.Test;
 import org.squiddev.cobalt.Constants;
+import org.squiddev.cobalt.LuaError;
 import org.squiddev.cobalt.LuaTable;
 import org.squiddev.cobalt.ValueFactory;
 
@@ -18,7 +19,11 @@
 class VarargArgumentsTest {
     private static LuaTable tableWithCustomType() {
         var metatable = new LuaTable();
-        metatable.rawset(Constants.NAME, ValueFactory.valueOf("some type"));
+        try {
+            metatable.rawset(Constants.NAME, ValueFactory.valueOf("some type"));
+        } catch (LuaError e) {
+            throw new IllegalStateException("Cannot create metatable", e);
+        }
 
         var table = new LuaTable();
         table.setMetatable(null, metatable);
diff --git a/projects/core/src/test/resources/test-rom/spec/base_spec.lua b/projects/core/src/test/resources/test-rom/spec/base_spec.lua
index fe37fb6530..5ea044f371 100644
--- a/projects/core/src/test/resources/test-rom/spec/base_spec.lua
+++ b/projects/core/src/test/resources/test-rom/spec/base_spec.lua
@@ -79,20 +79,6 @@ describe("The Lua base library", function()
     end)
 
     describe("load", function()
-        it("validates arguments", function()
-            load("")
-            load(function()
-            end)
-            load("", "")
-            load("", "", "")
-            load("", "", "", _ENV)
-
-            expect.error(load, nil):eq("bad argument #1 (function or string expected, got nil)")
-            expect.error(load, "", false):eq("bad argument #2 (string expected, got boolean)")
-            expect.error(load, "", "", false):eq("bad argument #3 (string expected, got boolean)")
-            expect.error(load, "", "", "", false):eq("bad argument #4 (table expected, got boolean)")
-        end)
-
         local function generator(parts)
             return coroutine.wrap(function()
                 for i = 1, #parts do
diff --git a/projects/core/src/test/resources/test-rom/spec/programs/shell_spec.lua b/projects/core/src/test/resources/test-rom/spec/programs/shell_spec.lua
index 92e19172a4..bdd4ed99ca 100644
--- a/projects/core/src/test/resources/test-rom/spec/programs/shell_spec.lua
+++ b/projects/core/src/test/resources/test-rom/spec/programs/shell_spec.lua
@@ -214,7 +214,7 @@ describe("The shell", function()
             local lines = {}
             for i = 1, 5 do lines[i] = win.getLine(i):gsub(" +$", "") end
             expect(lines):same {
-                "CraftOS 1.8",
+                "CraftOS 1.9",
                 "> xyz",
                 "Transferring transfer.txt",
                 "> xyz",