diff --git a/src/compiler/irgen.js b/src/compiler/irgen.js
index b5864de0..8614c20e 100644
--- a/src/compiler/irgen.js
+++ b/src/compiler/irgen.js
@@ -1120,6 +1120,7 @@ class ScriptTreeGenerator {
 
             const addonBlock = this.runtime.getAddonBlock(procedureCode);
             if (addonBlock) {
+                this.script.yields = true;
                 const args = {};
                 for (let i = 0; i < paramIds.length; i++) {
                     let value;
diff --git a/src/compiler/jsexecute.js b/src/compiler/jsexecute.js
index 6e2091c1..2d9005ef 100644
--- a/src/compiler/jsexecute.js
+++ b/src/compiler/jsexecute.js
@@ -203,7 +203,7 @@ const executeInCompatibilityLayer = function*(inputs, blockFunction, useFlags) {
  * @param {string} blockId The ID of the block being run
  * @param {object} args The arguments to pass to the block
  */
-const callAddonBlock = (procedureCode, blockId, args) => {
+const callAddonBlock = function*(procedureCode, blockId, args) {
     const addonBlock = thread.target.runtime.getAddonBlock(procedureCode);
     if (addonBlock) {
         const target = thread.target;
@@ -214,6 +214,9 @@ const callAddonBlock = (procedureCode, blockId, args) => {
             },
             target
         });
+        if (thread.status === Thread.STATUS_PROMISE_WAIT) {
+            yield;
+        }
     }
 };
 
diff --git a/src/compiler/jsgen.js b/src/compiler/jsgen.js
index cbe82f95..d176b3eb 100644
--- a/src/compiler/jsgen.js
+++ b/src/compiler/jsgen.js
@@ -658,7 +658,8 @@ class JSGenerator {
     descendStackedBlock (node) {
         switch (node.kind) {
         case 'addons.call':
-            this.source += `callAddonBlock("${sanitize(node.code)}","${sanitize(node.blockId)}",{`;
+            this.source += `yield* callAddonBlock("${sanitize(node.code)}","${sanitize(node.blockId)}",{`;
+            this.yielded();
             for (const argumentName of Object.keys(node.arguments)) {
                 const argumentValue = node.arguments[argumentName];
                 this.source += `"${sanitize(argumentName)}":${this.descendInput(argumentValue).asSafe()},`;