diff --git a/internal/abi/fastly/hostcalls_guest.go b/internal/abi/fastly/hostcalls_guest.go
index c5d8d18d..7e8a3870 100644
--- a/internal/abi/fastly/hostcalls_guest.go
+++ b/internal/abi/fastly/hostcalls_guest.go
@@ -15,10 +15,6 @@ import (
 	"github.com/fastly/compute-sdk-go/internal/abi/prim"
 )
 
-func init() {
-	fastlyABIInit(1)
-}
-
 // witx:
 //
 //	(module $fastly_abi
@@ -32,11 +28,10 @@ func init() {
 //go:noescape
 func fastlyABIInit(abiVersion prim.U64) FastlyStatus
 
-// TODO(pb): this doesn't need to be exported, I don't think?
 // Initialize the Fastly ABI at the given version.
-//func Initialize(version uint64) error {
-//	return fastlyABIInit(version).toError()
-//}
+func Initialize(version uint64) error {
+	return fastlyABIInit(prim.U64(version)).toError()
+}
 
 // witx:
 //
diff --git a/internal/abi/fastly/hostcalls_noguest.go b/internal/abi/fastly/hostcalls_noguest.go
index 12e559b8..7ace1c6c 100644
--- a/internal/abi/fastly/hostcalls_noguest.go
+++ b/internal/abi/fastly/hostcalls_noguest.go
@@ -13,6 +13,10 @@ import (
 	"net"
 )
 
+func Initialize(version uint64) error {
+	return fmt.Errorf("not implemented")
+}
+
 func ParseUserAgent(userAgent string) (family, major, minor, patch string, err error) {
 	return "", "", "", "", fmt.Errorf("not implemented")
 }