diff --git a/Earthfile b/Earthfile
index 097cd3d0..33eaa695 100644
--- a/Earthfile
+++ b/Earthfile
@@ -335,7 +335,7 @@ aws-ndll:
     SAVE ARTIFACT /workspace/haxelib_global/aws-sdk-neko/*/ndll/Linux64/aws.ndll
 
 haxelib-server-builder:
-    FROM haxe:4.3
+    FROM haxe:3.4
 
     WORKDIR /workspace
     COPY lib/record-macros lib/record-macros
@@ -516,7 +516,7 @@ ci-tests:
     COPY *.hxml .
 
     # for package.hxml
-    COPY haxelib.json README.md . 
+    COPY haxelib.json README.md .
     COPY +run.n/run.n .
 
     COPY +ci-runner/ci.n bin/ci.n
diff --git a/src/haxelib/Data.hx b/src/haxelib/Data.hx
index 3b8a5db3..58e06923 100644
--- a/src/haxelib/Data.hx
+++ b/src/haxelib/Data.hx
@@ -35,7 +35,7 @@ using StringTools;
 using Lambda;
 
 /** The level of strictness with which a `haxelib.json` check is performed. **/
-enum abstract CheckLevel(Int) {
+#if haxe4 enum #else @:enum #end abstract CheckLevel(Int) {
 	/** No check is performed. **/
 	var NoCheck = 0;
 	/** Only the syntax of the file is checked. **/
@@ -183,7 +183,7 @@ typedef DefineDocumentation = {
 }
 
 /** An abstract enum representing the different Licenses a project can have. **/
-enum abstract License(String) to String {
+#if haxe4 enum #else @:enum #end abstract License(String) to String {
 	var Gpl = 'GPL';
 	var Lgpl = 'LGPL';
 	var Mit = 'MIT';
diff --git a/src/haxelib/VersionData.hx b/src/haxelib/VersionData.hx
index f2669e06..6597cdec 100644
--- a/src/haxelib/VersionData.hx
+++ b/src/haxelib/VersionData.hx
@@ -1,7 +1,7 @@
 package haxelib;
 
 /** Abstract enum representing the types of Vcs systems that are supported. **/
-enum abstract VcsID(String) to String {
+#if haxe4 enum #else @:enum #end abstract VcsID(String) to String {
 	var Hg = "hg";
 	var Git = "git";