diff --git a/tools/isobuild/compiler-plugin.js b/tools/isobuild/compiler-plugin.js
index 3f368886c9..22a2852cd6 100644
--- a/tools/isobuild/compiler-plugin.js
+++ b/tools/isobuild/compiler-plugin.js
@@ -1072,7 +1072,10 @@ export class PackageSourceBatch {
     // depends on something).
     self.importedSymbolToPackageName = {}; // map from symbol to supplying package name
 
-    self.deps = [];
+
+    // List of packages (including weak) that need to load before
+    // this unibuild
+    self.orderedDeps = new Set();
   }
 
   async init() {
@@ -1095,17 +1098,26 @@ export class PackageSourceBatch {
       skipDebugOnly: true,
       skipProdOnly: true,
       skipTestOnly: true,
-    }, (depUnibuild, { weak, unordered }) => {
+    }, (depUnibuild) => {
       let packageName = depUnibuild.pkg.name;
 
+      self.orderedDeps.add(packageName);
+
       _.each(depUnibuild.declaredExports, function (symbol) {
         // Slightly hacky implementation of test-only exports.
         if (! symbol.testOnly || self.unibuild.pkg.isTest) {
           self.importedSymbolToPackageName[symbol.name] = packageName;
         }
       });
+    });
 
-      self.deps.push({ package: packageName, weak, unordered });
+    // At this point we can't easily know all weak dependencies
+    // that are actually used to pass them to eachUsedUnibuild.
+    // So instead we loop over the packages again to add them.
+    self.unibuild.uses.forEach(uses => {
+      if (uses.weak) {
+        self.orderedDeps.add(uses.package);
+      }
     });
 
     self.useMeteorInstall =
@@ -1700,7 +1712,7 @@ export class PackageSourceBatch {
       imports: self.importedSymbolToPackageName,
       // XXX report an error if there is a package called global-imports
       includeSourceMapInstructions: isWeb,
-      deps: self.deps
+      orderedDeps: Array.from(self.orderedDeps)
     };
 
     const fileHashes = [];
diff --git a/tools/isobuild/linker.js b/tools/isobuild/linker.js
index 31d6ed990e..3ac5c50fcd 100644
--- a/tools/isobuild/linker.js
+++ b/tools/isobuild/linker.js
@@ -941,12 +941,8 @@ var getHeader = function (options) {
 
   var isApp = options.name === null;
   var chunks = [];
-   let orderedDeps = [];
-
-  options.deps.forEach(dep => {
-    if (!dep.unordered) {
-      orderedDeps.push(JSON.stringify(dep.package))
-    }
+  let orderedDeps = options.orderedDeps.map(packageName => {
+    return JSON.stringify(packageName);
   });
 
   chunks.push(
@@ -1140,9 +1136,9 @@ export var fullLink = Profile("linker.fullLink", async function (inputFiles, {
   // how to use them in a browser.
   includeSourceMapInstructions,
 
-  // List of packages this bundle directly uses, or is implied by the packages
-  // it uses
-  deps
+  // List of packages this bundle directly uses that need to load
+  // first. Includes weak dependencies.
+  orderedDeps
 }) {
   buildmessage.assertInJob();
 
@@ -1159,7 +1155,7 @@ export var fullLink = Profile("linker.fullLink", async function (inputFiles, {
   // we can be sure the runtime will be available
   // The main situations it is not available is the core-runtime
   // package itself, or any build plugins with no dependencies
-  let hasRuntime = deps.some(entry => entry.unordered !== true);
+  let hasRuntime = orderedDeps.length > 0;
 
   _.each(inputFiles, file => module.addFile(file));
 
@@ -1194,7 +1190,7 @@ export var fullLink = Profile("linker.fullLink", async function (inputFiles, {
         imports,
         packageVariables: [],
         hasRuntime,
-        deps
+        orderedDeps
       });
       let footer = getFooter({
         name: null,
@@ -1255,7 +1251,7 @@ export var fullLink = Profile("linker.fullLink", async function (inputFiles, {
     imports,
     packageVariables: _.union(assignedVariables, declaredExports),
     hasRuntime,
-    deps
+    orderedDeps
   });
 
   var footer = getFooter({