diff --git a/launcher/src/main/java/com/skcraft/launcher/model/minecraft/Library.java b/launcher/src/main/java/com/skcraft/launcher/model/minecraft/Library.java
index a6acd7f..7f49c7e 100644
--- a/launcher/src/main/java/com/skcraft/launcher/model/minecraft/Library.java
+++ b/launcher/src/main/java/com/skcraft/launcher/model/minecraft/Library.java
@@ -65,10 +65,32 @@
         }
     }
 
+    /**
+     * BACKWARDS COMPATIBILITY:
+     * Some library definitions only come with a "name" key and don't trigger any other compatibility measures.
+     * Therefore, if a library has no artifacts when this is called, we call {@link #setServerreq)} to trigger
+     * artifact generation that assumes the source is the Minecraft libraries URL.
+     * There is also some special handling for natives in this function; if we have no extra artifacts (newer specs
+     * put this in "classifiers" in the download list) then we make up an artifact by adding a maven classifier to
+     * the library name and using that.
+     */
     public Artifact getArtifact(Environment environment) {
+        if (getDownloads() == null) {
+            setServerreq(true); // BACKWARDS COMPATIBILITY
+        }
+
         String nativeString = getNativeString(environment.getPlatform());
 
         if (nativeString != null) {
+            if (getDownloads().getClassifiers() == null) {
+                // BACKWARDS COMPATIBILITY: make up a virtual artifact
+                Artifact virtualArtifact = new Artifact();
+                virtualArtifact.setUrl(getDownloads().getArtifact().getUrl());
+                virtualArtifact.setPath(mavenNameToPath(name + ":" + nativeString));
+
+                return virtualArtifact;
+            }
+
             return getDownloads().getClassifiers().get(nativeString);
         } else {
             return getDownloads().getArtifact();
@@ -121,7 +143,13 @@
         private Map<String, Artifact> classifiers;
     }
 
-    // Support for old Forge distributions with legacy library specs.
+    /**
+     * BACKWARDS COMPATIBILITY:
+     * Various sources use the old-style library specification, where there are two keys - "name" and "url",
+     * rather than the newer multiple-artifact style. This setter is called by Jackson when the "url" property
+     * is present, and uses it to create a "virtual" artifact using the URL given to us here plus the library
+     * name parsed out into a path.
+     */
     public void setUrl(String url) {
         Artifact virtualArtifact = new Artifact();
 
@@ -134,9 +162,14 @@
         setDownloads(downloads);
     }
 
+    /**
+     * BACKWARDS COMPATIBILITY:
+     * Some old Forge distributions use a parameter called "serverreq" to indicate that the dependency should
+     * be fetched from the Minecraft library source; this setter handles that.
+     */
     public void setServerreq(boolean value) {
         if (value) {
-            setUrl("https://libraries.minecraft.net/"); // TODO do something better than this
+            setUrl("https://libraries.minecraft.net/"); // TODO get this from properties?
         }
     }
 
diff --git a/launcher/src/main/java/com/skcraft/launcher/update/Updater.java b/launcher/src/main/java/com/skcraft/launcher/update/Updater.java
index cf9c322..083dfde 100644
--- a/launcher/src/main/java/com/skcraft/launcher/update/Updater.java
+++ b/launcher/src/main/java/com/skcraft/launcher/update/Updater.java
@@ -102,30 +102,48 @@
         return instance;
     }
 
+    /**
+     * Check whether the package manifest contains an embedded version manifest,
+     * otherwise we'll have to download the one for the given Minecraft version.
+     *
+     * BACKWARDS COMPATIBILITY:
+     * Old manifests have an embedded version manifest without the minecraft JARs list present.
+     * If we find a manifest without that jar list, fetch the newer copy from launchermeta and use the list from that.
+     * We can't just replace the manifest outright because library versions might differ and that screws up Runner.
+     */
     private VersionManifest readVersionManifest(Manifest manifest) throws IOException, InterruptedException {
-        // Check whether the package manifest contains an embedded version manifest,
-        // otherwise we'll have to download the one for the given Minecraft version
         VersionManifest version = manifest.getVersionManifest();
-        if (version != null) {
-            mapper.writeValue(instance.getVersionPath(), version);
-            return version;
-        } else {
-            URL url = url(launcher.getProperties().getProperty("versionManifestUrl"));
+        URL url = url(launcher.getProperties().getProperty("versionManifestUrl"));
 
-            ReleaseList releases = HttpRequest.get(url)
-                    .execute()
-                    .expectResponseCode(200)
-                    .returnContent()
-                    .asJson(ReleaseList.class);
-
-            Version relVersion = releases.find(manifest.getGameVersion());
-            return HttpRequest.get(url(relVersion.getUrl()))
-                    .execute()
-                    .expectResponseCode(200)
-                    .returnContent()
-                    .saveContent(instance.getVersionPath())
-                    .asJson(VersionManifest.class);
+        if (version == null) {
+            version = fetchVersionManifest(url, manifest);
         }
+
+        if (version.getDownloads().isEmpty()) {
+            // Backwards compatibility hack
+            VersionManifest otherManifest = fetchVersionManifest(url, manifest);
+
+            version.setDownloads(otherManifest.getDownloads());
+            version.setAssetIndex(otherManifest.getAssetIndex());
+        }
+
+        mapper.writeValue(instance.getVersionPath(), version);
+        return version;
+    }
+
+    private static VersionManifest fetchVersionManifest(URL url, Manifest manifest) throws IOException, InterruptedException {
+        ReleaseList releases = HttpRequest.get(url)
+                .execute()
+                .expectResponseCode(200)
+                .returnContent()
+                .asJson(ReleaseList.class);
+
+        Version relVersion = releases.find(manifest.getGameVersion());
+        return HttpRequest.get(url(relVersion.getUrl()))
+                .execute()
+                .expectResponseCode(200)
+                .returnContent()
+                .asJson(VersionManifest.class);
     }
 
     /**