diff --git a/generator/src/openapi.rs b/generator/src/openapi.rs
index 3301edb..0540688 100644
--- a/generator/src/openapi.rs
+++ b/generator/src/openapi.rs
@@ -92,7 +92,7 @@ pub struct ExternalDocs {
 pub struct Parameter {
     pub name: String,
     #[serde(rename = "in")]
-    pub _in: String,
+    pub _in: ParameterIn,
     pub description: Option<String>,
     pub required: Option<bool>,
     pub schema: Option<MaybeRef<Schema>>,
@@ -118,6 +118,16 @@ pub struct Parameter {
     pub multiple_of: Option<u64>,
 }
 
+#[derive(serde::Deserialize, Debug, PartialEq)]
+#[serde(rename_all(deserialize = "camelCase"))]
+pub enum ParameterIn {
+    Path,
+    Query,
+    Header,
+    Body,
+    FormData,
+}
+
 #[derive(serde::Deserialize, Debug, PartialEq)]
 #[serde(rename_all(deserialize = "camelCase"))]
 pub enum ParameterType {