diff --git a/src/NetscriptJSEvaluator.ts b/src/NetscriptJSEvaluator.ts
index d706d3066..ddd41b2f4 100644
--- a/src/NetscriptJSEvaluator.ts
+++ b/src/NetscriptJSEvaluator.ts
@@ -82,6 +82,16 @@ export async function executeJSScript(
   return loadedModule.main(ns);
 }
 
+function isDependencyOutOfDate(filename: string, scripts: Script[], scriptModuleSequenceNumber: number): boolean {
+  const depScript = scripts.find((s) => s.filename == filename);
+
+  // If the script is not present on the server, we should recompile, if only to get any necessary
+  // compilation errors.
+  if (!depScript) return true;
+
+  const depIsMoreRecent = depScript.moduleSequenceNumber > scriptModuleSequenceNumber;
+  return depIsMoreRecent;
+}
 /** Returns whether we should compile the script parameter.
  *
  * @param {Script} script
@@ -89,16 +99,7 @@ export async function executeJSScript(
  */
 function shouldCompile(script: Script, scripts: Script[]): boolean {
   if (script.module === "") return true;
-  return script.dependencies.some((dep) => {
-    const depScript = scripts.find((s) => s.filename == dep.filename);
-
-    // If the script is not present on the server, we should recompile, if only to get any necessary
-    // compilation errors.
-    if (!depScript) return true;
-
-    const depIsMoreRecent = depScript.moduleSequenceNumber > script.moduleSequenceNumber;
-    return depIsMoreRecent;
-  });
+  return script.dependencies.some((dep) => isDependencyOutOfDate(dep.filename, scripts, script.moduleSequenceNumber));
 }
 
 // Gets a stack of blob urls, the top/right-most element being
@@ -123,8 +124,13 @@ function shouldCompile(script: Script, scripts: Script[]): boolean {
 // BUG: apparently seen is never consulted. Oops.
 function _getScriptUrls(script: Script, scripts: Script[], seen: Script[]): ScriptUrl[] {
   // Inspired by: https://stackoverflow.com/a/43834063/91401
-  /** @type {ScriptUrl[]} */
-  const urlStack = [];
+  const urlStack: ScriptUrl[] = [];
+  // Seen contains the dependents of the current script. Make sure we include that in the script dependents.
+  for (const dependent of seen) {
+    if (!script.dependents.some(s => s.server === dependent.server && s.filename == dependent.filename)) {
+      script.dependents.push({ server: dependent.server, filename: dependent.filename });
+    }
+  }
   seen.push(script);
   try {
     // Replace every import statement with an import to a blob url containing
@@ -187,6 +193,19 @@ function _getScriptUrls(script: Script, scripts: Script[], seen: Script[]): Scri
       // Check to see if the urls for this script are stored in the cache by the hash value.
       let urls = ImportCache.get(importedScript.hash());
       // If we don't have it in the cache, then we need to generate the urls for it.
+      if (urls) {
+          // Verify that these urls are valid and have not been updated.
+          for(const url of urls) {
+            if (isDependencyOutOfDate(url.filename, scripts, url.moduleSequenceNumber)) {
+              // Revoke these URLs from the browser. We will be unable to use them again.
+              for (const url of urls) URL.revokeObjectURL(url.url);
+              // Clear the cache and prepare for new blobs.
+              urls = null;
+              ImportCache.remove(importedScript.hash());
+              break;
+            }
+          }
+      }
       if (!urls) {
         // Try to get a URL for the requested script and its dependencies.
         urls = _getScriptUrls(importedScript, scripts, seen);
@@ -217,7 +236,7 @@ function _getScriptUrls(script: Script, scripts: Script[], seen: Script[]): Scri
     // (e.g. same scripts on server, same hash value, etc) can use this blob url.
     BlobCache.store(transformedHash, blob);
     // Push the blob URL onto the top of the stack.
-    urlStack.push(new ScriptUrl(script.filename, blob));
+    urlStack.push(new ScriptUrl(script.filename, blob, script.moduleSequenceNumber));
     return urlStack;
   } catch (err) {
     // If there is an error, we need to clean up the URLs.
diff --git a/src/Script/Script.ts b/src/Script/Script.ts
index d6b13dbff..393e08091 100644
--- a/src/Script/Script.ts
+++ b/src/Script/Script.ts
@@ -10,10 +10,13 @@ import { ScriptUrl } from "./ScriptUrl";
 import { Generic_fromJSON, Generic_toJSON, Reviver } from "../utils/JSONReviver";
 import { roundToTwo } from "../utils/helpers/roundToTwo";
 import { computeHash } from "../utils/helpers/computeHash";
+import { ImportCache } from "../utils/ImportCache";
 import { IPlayer } from "../PersonObjects/IPlayer";
 
 let globalModuleSequenceNumber = 0;
 
+interface ScriptReference { filename: string; server: string }
+
 export class Script {
   // Code for this script
   code = "";
@@ -35,6 +38,7 @@ export class Script {
   // whenever the script is first evaluated, and therefore may be out of date if the script
   // has been updated since it was last run.
   dependencies: ScriptUrl[] = [];
+  dependents: ScriptReference[] = [];
 
   // Amount of RAM this Script requres to run
   ramUsage = 0;
@@ -99,7 +103,11 @@ export class Script {
    * Force update of the computed hash based on the source code.
    */
   rehash(): void {
+    const oldHash = this._hash;
     this._hash = computeHash(this.code);
+    if (oldHash !== this._hash) {
+      ImportCache.remove(oldHash);
+    }
   }
 
   /**
@@ -124,6 +132,10 @@ export class Script {
     this.server = hostname;
     this.updateRamUsage(player, otherScripts);
     this.markUpdated();
+    for (const dependent of this.dependents) {
+      const [dependentScript] = otherScripts.filter(s => s.filename === dependent.filename && s.server == dependent.server);
+      if (dependentScript !== null) dependentScript.markUpdated();
+    }
   }
 
   /**
@@ -156,6 +168,7 @@ export class Script {
     s.url = "";
     // Rehash the code to ensure that hash is set properly.
     s.rehash();
+    s.dependents = [];
     return s;
   }
 
diff --git a/src/Script/ScriptUrl.ts b/src/Script/ScriptUrl.ts
index 037189147..1dedf89b5 100644
--- a/src/Script/ScriptUrl.ts
+++ b/src/Script/ScriptUrl.ts
@@ -1,9 +1,11 @@
 export class ScriptUrl {
   filename: string;
   url: string;
+  moduleSequenceNumber: number;
 
-  constructor(filename: string, url: string) {
+  constructor(filename: string, url: string, moduleSequenceNumber: number) {
     this.filename = filename;
     this.url = url;
+    this.moduleSequenceNumber = moduleSequenceNumber;
   }
 }
diff --git a/src/utils/ImportCache.ts b/src/utils/ImportCache.ts
index 9a8383e21..ffeb845e8 100644
--- a/src/utils/ImportCache.ts
+++ b/src/utils/ImportCache.ts
@@ -3,12 +3,16 @@ import { ScriptUrl } from "../Script/ScriptUrl";
 const importCache: { [hash: string]: ScriptUrl[] } = {};
 
 export class ImportCache {
-  static get(hash: string): ScriptUrl[] {
-    return importCache[hash];
+  static get(hash: string): ScriptUrl[] | null {
+    return importCache[hash] || null;
   }
 
   static store(hash: string, value: ScriptUrl[]): void {
     if (importCache[hash]) return;
     importCache[hash] = value;
   }
+
+  static remove(hash: string): void {
+    delete importCache[hash];
+  }
 }