diff --git a/config.go b/config.go
index 12fdeb73..d66d2d68 100644
--- a/config.go
+++ b/config.go
@@ -23,6 +23,7 @@ import (
 	"regexp"
 
 	interfaces "github.com/loopholelabs/scale-signature-interfaces"
+	"github.com/loopholelabs/scale/extension"
 	"github.com/loopholelabs/scale/scalefunc"
 )
 
@@ -49,6 +50,8 @@ type Config[T interfaces.Signature] struct {
 	context      context.Context
 	Stdout       io.Writer
 	Stderr       io.Writer
+
+	extensions map[string]extension.InstallableFunc
 }
 
 // NewConfig returns a new Scale Runtime Config
@@ -84,6 +87,17 @@ func (c *Config[T]) validate() error {
 	return nil
 }
 
+func (c *Config[T]) WithExtensions(e map[string]extension.InstallableFunc) *Config[T] {
+	if c.extensions == nil {
+		c.extensions = make(map[string]extension.InstallableFunc)
+	}
+	for n, f := range e {
+		// TODO: Check for stomping etc
+		c.extensions[n] = f
+	}
+	return c
+}
+
 func (c *Config[T]) WithSignature(newSignature interfaces.New[T]) *Config[T] {
 	c.newSignature = newSignature
 	return c
diff --git a/extension/generator/templates/guest.go.templ b/extension/generator/templates/guest.go.templ
index e0c18c9f..13728c98 100644
--- a/extension/generator/templates/guest.go.templ
+++ b/extension/generator/templates/guest.go.templ
@@ -87,7 +87,7 @@ func ext_{{ $schema.Name }}_{{ $ifc.Name }}_{{ $fn.Name }}(instance uint64, offs
 
 //export ext_{{ $schema.Name }}_{{ $fn.Name }}
 //go:linkname ext_{{ $schema.Name }}_{{ $fn.Name }}
-func ext_{{ $schema.Name }}_{{ $fn.Name }}(offset uint32, length uint32) uint64
+func ext_{{ $schema.Name }}_{{ $fn.Name }}(instance uint64, offset uint32, length uint32) uint64
 
 func {{ $fn.Name }}(params *{{ $fn.Params }}) ({{ $fn.Return }}, error) {
   // First we take the params, serialize them.
@@ -102,7 +102,7 @@ func {{ $fn.Name }}(params *{{ $fn.Params }}) ({{ $fn.Return }}, error) {
   // Now make the call to the host.
 
   {{- if (IsInterface $schema $fn.Return) }}
-    v := ext_{{ $schema.Name }}_{{ $fn.Name }}(off, l)
+    v := ext_{{ $schema.Name }}_{{ $fn.Name }}(0, off, l)
     // IF the return type is an interface return ifc, which contains hidden instanceId.
 
     // TODO: Handle error from host. In this case there'll be an error in the readBuffer
@@ -113,7 +113,7 @@ func {{ $fn.Name }}(params *{{ $fn.Params }}) ({{ $fn.Return }}, error) {
 
     return ret, nil
   {{ else }}
-    ext_{{ $schema.Name }}_{{ $fn.Name }}(off, l)
+    ext_{{ $schema.Name }}_{{ $fn.Name }}(0, off, l)
     // IF the return type is a model, we should read the data from the read buffer.
 
     ret := &{{ $fn.Return }}{}
diff --git a/scale.go b/scale.go
index 0ca8d7c3..6e5262fb 100644
--- a/scale.go
+++ b/scale.go
@@ -28,6 +28,8 @@ import (
 	"github.com/tetratelabs/wazero"
 	"github.com/tetratelabs/wazero/api"
 	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
+
+	"github.com/loopholelabs/scale/extension"
 )
 
 // Next is the next function in the middleware chain. It's meant to be implemented
@@ -82,7 +84,29 @@ func (r *Scale[T]) init() error {
 		r.moduleConfig = r.moduleConfig.WithStderr(r.config.Stderr)
 	}
 
-	envHostModuleBuilder := r.runtime.NewHostModuleBuilder("env").
+	envModule := r.runtime.NewHostModuleBuilder("env")
+
+	// Install any extensions...
+	for name, fn := range r.config.extensions {
+		fmt.Printf("Installing module [%s]\n", name)
+		wfn := func(n string, f extension.InstallableFunc) func(context.Context, api.Module, []uint64) {
+			return func(ctx context.Context, mod api.Module, params []uint64) {
+				fmt.Printf("HOST FUNCTION CALLED %s\n", n)
+				mem := mod.Memory()
+				resize := func(name string, size uint64) (uint64, error) {
+					w, err := mod.ExportedFunction(name).Call(context.Background(), size)
+					return w[0], err
+				}
+				f(mem, resize, params)
+			}
+		}(name, fn)
+
+		envModule.NewFunctionBuilder().
+			WithGoModuleFunction(api.GoModuleFunc(wfn), []api.ValueType{api.ValueTypeI64, api.ValueTypeI32, api.ValueTypeI32}, []api.ValueType{api.ValueTypeI64}).
+			WithParameterNames("instance", "pointer", "length").Export(name)
+	}
+
+	envHostModuleBuilder := envModule.
 		NewFunctionBuilder().
 		WithGoModuleFunction(api.GoModuleFunc(r.next), []api.ValueType{api.ValueTypeI32, api.ValueTypeI32}, []api.ValueType{}).
 		WithParameterNames("pointer", "length").Export("next")
diff --git a/storage/extension.go b/storage/extension.go
index f72ad14a..9771c5ef 100644
--- a/storage/extension.go
+++ b/storage/extension.go
@@ -320,7 +320,10 @@ func GenerateExtension(ext *extension.Schema, name string, tag string, org strin
 	}
 
 	hostPackage, err := generator.GenerateHostLocal(&generator.Options{
-		Extension: ext,
+		Extension:               ext,
+		GolangPackageImportPath: "extension",
+		GolangPackageName:       ext.Name,
+		GolangPackageVersion:    "v0.1.0",
 	})
 	if err != nil {
 		return err