diff --git a/.changeset/warm-scissors-live.md b/.changeset/warm-scissors-live.md
new file mode 100644
index 00000000..8df5cb1f
--- /dev/null
+++ b/.changeset/warm-scissors-live.md
@@ -0,0 +1,5 @@
+---
+"openapi-zod-client": patch
+---
+
+When a property from an external json or yaml file starts with a number, e.g. 1st, instead of first, the generated Zod-Schema is corrupt. The change in the wrapWithQuotesIfNeeded method makes sure, that any property starting with a number is wrapped in quotes.
diff --git a/lib/src/utils.ts b/lib/src/utils.ts
index 7f626d9c..6d7986a5 100644
--- a/lib/src/utils.ts
+++ b/lib/src/utils.ts
@@ -15,7 +15,7 @@ export function normalizeString(text: string) {
 }
 
 export const wrapWithQuotesIfNeeded = (str: string) => {
-    if (/^\w+$/.test(str)) {
+    if (/^[a-zA-Z]\w*$/.test(str)) {
         return str;
     }
 
diff --git a/lib/tests/ref-in-another-file.test.ts b/lib/tests/ref-in-another-file.test.ts
index 74b2e026..c11bea03 100644
--- a/lib/tests/ref-in-another-file.test.ts
+++ b/lib/tests/ref-in-another-file.test.ts
@@ -19,7 +19,7 @@ test("ref-in-another-file", async () => {
                   "parameters": [],
                   "path": "/robots.txt",
                   "requestFormat": "json",
-                  "response": "z.object({ name: z.string(), completed: z.boolean() }).passthrough()",
+                  "response": "z.object({ name: z.string(), completed: z.boolean(), "0_property_starting_with_number": z.number() }).passthrough()",
               },
           ],
           "issues": {
diff --git a/lib/tests/ref-in-another-file/single-schema.yaml b/lib/tests/ref-in-another-file/single-schema.yaml
index 1112e105..09283a28 100644
--- a/lib/tests/ref-in-another-file/single-schema.yaml
+++ b/lib/tests/ref-in-another-file/single-schema.yaml
@@ -5,6 +5,9 @@ properties:
     type: string
   completed:
     type: boolean
+  0_property_starting_with_number:
+    type: number
 required:
   - name
   - completed
+  - 0_property_starting_with_number