diff --git a/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ABI.java b/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ABI.java
index 8ad6f2c..c23fccc 100644
--- a/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ABI.java
+++ b/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ABI.java
@@ -22,11 +22,12 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 @HostModule("env")
 class ABI {
 
-    private Handler handler;
+    private final Handler handler;
     private Memory memory;
     ExportFunction initializeFn;
     ExportFunction mainFn;
@@ -58,12 +59,8 @@ class ABI {
     ExportFunction proxyOnQueueReadyFn;
     ExportFunction proxyOnForeignFunctionFn;
 
-    Handler getHandler() {
-        return handler;
-    }
-
-    void setHandler(Handler handler) {
-        this.handler = handler;
+    ABI(Handler handler) {
+        this.handler = Objects.requireNonNull(handler);
     }
 
     void setInstance(Instance instance) {
diff --git a/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ABI_WASI.java b/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ABI_WASI.java
index bd22831..2abc079 100644
--- a/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ABI_WASI.java
+++ b/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ABI_WASI.java
@@ -11,6 +11,7 @@
 import io.roastedroot.proxywasm.LogLevel;
 import io.roastedroot.proxywasm.WasmException;
 import java.nio.charset.StandardCharsets;
+import java.util.Objects;
 
 /**
  * Implements a restricted subset of the WASI ABI, specifically so that a WASM module can
@@ -29,7 +30,7 @@ public class ABI_WASI {
     private final Handler handler;
 
     public ABI_WASI(Handler handler) {
-        this.handler = handler;
+        this.handler = Objects.requireNonNull(handler);
     }
 
     ////////////////////////////////////////////////////////////////////////////
diff --git a/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ProxyWasm.java b/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ProxyWasm.java
index 54e8df9..f6006ae 100644
--- a/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ProxyWasm.java
+++ b/proxy-wasm-java-host/src/main/java/io/roastedroot/proxywasm/internal/ProxyWasm.java
@@ -36,19 +36,7 @@ public final class ProxyWasm implements Closeable {
 
     private ProxyWasm(Builder other) throws StartException {
         this.pluginHandler = Objects.requireNonNullElse(other.pluginHandler, new Handler() {});
-        this.abi = other.abi;
-        this.abi.setHandler(createImportsHandler());
-
-        // initialize/start the vm
-        if (this.abi.initialize()) {
-            this.abi.main(0, 0);
-        } else {
-            this.abi.start();
-        }
-
-        if (other.start) {
-            start();
-        }
+        this.abi = new ABI(createImportsHandler());
     }
 
     public Handler getPluginHandler() {
@@ -251,13 +239,13 @@ ABI abi() {
 
     public static class Builder implements Cloneable {
 
-        private final ABI abi = new ABI();
-
         private Handler pluginHandler;
         private ImportMemory memory;
         private boolean start = true;
         private Function<Instance, Machine> machineFactory;
 
+        private Builder() {}
+
         @Override
         @SuppressWarnings("NoClone")
         protected Builder clone() {
@@ -288,24 +276,16 @@ public ProxyWasm.Builder withMachineFactory(Function<Instance, Machine> machineF
             return this;
         }
 
-        Builder() {}
-
-        public ProxyWasm build(Instance instance) throws StartException {
-            abi.setInstance(instance);
-            return new ProxyWasm(this.clone());
-        }
-
         public ProxyWasm build(WasmModule module) throws StartException {
-            return this.build(Instance.builder(module));
-        }
-
-        public ProxyWasm build(Instance.Builder instanceBuilder) throws StartException {
-            var imports = ImportValues.builder();
-
+            var instanceBuilder = Instance.builder(module);
             if (this.machineFactory != null) {
                 instanceBuilder.withMachineFactory(this.machineFactory);
             }
 
+            var proxyWasm = new ProxyWasm(this.clone());
+            ABI abi = proxyWasm.abi;
+
+            var imports = ImportValues.builder();
             imports.addMemory(Objects.requireNonNullElseGet(memory, this::defaultImportMemory));
             imports.addFunction(abi.toHostFunctions());
 
@@ -315,7 +295,18 @@ public ProxyWasm build(Instance.Builder instanceBuilder) throws StartException {
                             .withImportValues(imports.build())
                             .build();
 
-            return build(instance);
+            abi.setInstance(instance);
+
+            if (abi.initialize()) {
+                abi.main(0, 0);
+            } else {
+                abi.start();
+            }
+            if (start) {
+                proxyWasm.start();
+            }
+
+            return proxyWasm;
         }
 
         ImportMemory defaultImportMemory() {
diff --git a/proxy-wasm-java-host/src/test/java/io/roastedroot/proxywasm/examples/DispatchCallOnTickTest.java b/proxy-wasm-java-host/src/test/java/io/roastedroot/proxywasm/examples/DispatchCallOnTickTest.java
index 4284025..78507ee 100644
--- a/proxy-wasm-java-host/src/test/java/io/roastedroot/proxywasm/examples/DispatchCallOnTickTest.java
+++ b/proxy-wasm-java-host/src/test/java/io/roastedroot/proxywasm/examples/DispatchCallOnTickTest.java
@@ -2,8 +2,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import com.dylibso.chicory.experimental.aot.AotMachine;
-import com.dylibso.chicory.runtime.Instance;
+import com.dylibso.chicory.compiler.MachineFactoryCompiler;
 import com.dylibso.chicory.wasm.Parser;
 import com.dylibso.chicory.wasm.WasmModule;
 import io.roastedroot.proxywasm.StartException;
@@ -24,9 +23,11 @@ public class DispatchCallOnTickTest {
     @Test
     public void testOnTick() throws StartException {
         var handler = new MockHandler();
-        ProxyWasm.Builder builder = ProxyWasm.builder().withPluginHandler(handler);
-        var instanceBuilder = Instance.builder(module).withMachineFactory(AotMachine::new);
-        try (var host = builder.build(instanceBuilder)) {
+        ProxyWasm.Builder builder =
+                ProxyWasm.builder()
+                        .withPluginHandler(handler)
+                        .withMachineFactory(MachineFactoryCompiler::compile);
+        try (var host = builder.build(module)) {
             assertEquals(tickMilliseconds, handler.getTickPeriodMilliseconds());
 
             for (int i = 1; i <= 10; i++) {