diff --git a/packages/quicktype-core/src/language/TypeScriptZod/TypeScriptZodRenderer.ts b/packages/quicktype-core/src/language/TypeScriptZod/TypeScriptZodRenderer.ts
index 9b20eb1a0..073f93d0a 100644
--- a/packages/quicktype-core/src/language/TypeScriptZod/TypeScriptZodRenderer.ts
+++ b/packages/quicktype-core/src/language/TypeScriptZod/TypeScriptZodRenderer.ts
@@ -275,6 +275,22 @@ export class TypeScriptZodRenderer extends ConvenienceRenderer {
         return this._recursiveTypeRefs.has(t.typeRef);
     }
 
+    protected objectUnknownKeySuffix(t: ObjectType): Sourcelike {
+        const additionalProperties = t.getAdditionalProperties();
+        if (additionalProperties === undefined) {
+            return ".strict()";
+        }
+        if (additionalProperties.kind === "any") {
+            return ".passthrough()";
+        }
+
+        return [
+            ".catchall(",
+            this.typeMapTypeFor(additionalProperties, false),
+            ")",
+        ];
+    }
+
     protected emitObject(name: Name, t: ObjectType): void {
         if (this.isRecursive(t)) {
             this.emitLazyObject(name, t);
@@ -302,7 +318,11 @@ export class TypeScriptZodRenderer extends ConvenienceRenderer {
                 );
             });
         });
-        this.emitLine(hasOptionalConstructor ? "}));" : "});");
+        this.emitLine(
+            "})",
+            this.objectUnknownKeySuffix(t),
+            hasOptionalConstructor ? ");" : ";",
+        );
         if (!this._options.justSchema) {
             this.emitLine(
                 "export type ",
@@ -368,7 +388,7 @@ export class TypeScriptZodRenderer extends ConvenienceRenderer {
                     },
                 );
             });
-            this.emitLine("})");
+            this.emitLine("})", this.objectUnknownKeySuffix(t));
         });
         this.emitLine(");");
     }
@@ -444,8 +464,9 @@ export class TypeScriptZodRenderer extends ConvenienceRenderer {
                 }
             }
 
-            // Finally return the reference to a class as that will need to be defined (where objects, maps, unions, intersections and arrays do not)
-            if (type instanceof ClassType) {
+            // Finally return references to named classes and full objects as those
+            // need to be defined. Maps, unions, intersections, and arrays do not.
+            if (type instanceof ClassType || type.kind === "object") {
                 typeRefs.push(type.typeRef);
             }
         }
diff --git a/packages/quicktype-core/src/language/TypeScriptZod/language.ts b/packages/quicktype-core/src/language/TypeScriptZod/language.ts
index efe525f81..4dad7b935 100644
--- a/packages/quicktype-core/src/language/TypeScriptZod/language.ts
+++ b/packages/quicktype-core/src/language/TypeScriptZod/language.ts
@@ -54,6 +54,10 @@ export class TypeScriptZodTargetLanguage extends TargetLanguage<
         return true;
     }
 
+    public get supportsFullObjectType(): boolean {
+        return true;
+    }
+
     protected makeRenderer<Lang extends LanguageName = "typescript-zod">(
         renderContext: RenderContext,
         untypedOptionValues: RendererOptions<Lang>,
diff --git a/test/unit/typescript-zod-additional-properties.test.ts b/test/unit/typescript-zod-additional-properties.test.ts
new file mode 100644
index 000000000..e0a9336c6
--- /dev/null
+++ b/test/unit/typescript-zod-additional-properties.test.ts
@@ -0,0 +1,40 @@
+import { InputData, JSONSchemaInput, quicktype } from "quicktype-core";
+import { expect, test } from "vitest";
+
+test("TypeScript Zod preserves JSON Schema additionalProperties semantics", async () => {
+    const schemaInput = new JSONSchemaInput(undefined);
+    await schemaInput.addSource({
+        name: "TopLevel",
+        schema: JSON.stringify({
+            type: "object",
+            properties: {
+                strict: {
+                    type: "object",
+                    properties: { value: { type: "string" } },
+                    additionalProperties: false,
+                },
+                loose: {
+                    type: "object",
+                    properties: { value: { type: "string" } },
+                    additionalProperties: true,
+                },
+                typed: {
+                    type: "object",
+                    properties: { value: { type: "string" } },
+                    additionalProperties: { type: "boolean" },
+                },
+            },
+            required: ["strict", "loose", "typed"],
+            additionalProperties: false,
+        }),
+    });
+    const inputData = new InputData();
+    inputData.addInput(schemaInput);
+
+    const result = await quicktype({ inputData, lang: "typescript-zod" });
+    const output = result.lines.join("\n");
+
+    expect(output).toContain(".strict()");
+    expect(output).toContain(".passthrough()");
+    expect(output).toContain(".catchall(z.boolean())");
+});