diff --git a/src/NetscriptFunctions.js b/src/NetscriptFunctions.js
index 4bd3b4da3..799ca02df 100644
--- a/src/NetscriptFunctions.js
+++ b/src/NetscriptFunctions.js
@@ -229,7 +229,6 @@ function NetscriptFunctions(workerScript) {
                 workerScript.scriptRef.log("Sleeping for " + time + " milliseconds");
             }
             return netscriptDelay(time, workerScript).then(function() {
-                if (workerScript.env.stopFlag) {return Promise.reject(workerScript);}
                 return Promise.resolve(true);
             });
         },
diff --git a/src/NetscriptWorker.js b/src/NetscriptWorker.js
index e024d729c..0b5aa2a81 100644
--- a/src/NetscriptWorker.js
+++ b/src/NetscriptWorker.js
@@ -73,6 +73,13 @@ function startJsScript(workerScript) {
         // This function unfortunately cannot be an async function, because we don't
         // know if the original one was, and there's no way to tell.
         return function (...args) {
+            // Wrap every netscript function with a check for the stop flag.
+            // This prevents cases where we never stop because we are only calling
+            // netscript functions that don't check this.
+            // This is not a problem for legacy Netscript because it also checks the
+            // stop flag in the evaluator.
+            if (workerScript.env.stopFlag) {return Promise.reject(workerScript);}
+
             const msg = "Concurrent calls to Netscript functions not allowed! " +
                         "Did you forget to await hack(), grow(), or some other " +
                         "promise-returning function? (Currently running: %s tried to run: %s)"