diff --git a/Cargo.lock b/Cargo.lock
index 78c5eeb..61464a5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -413,6 +413,16 @@ version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
 
+[[package]]
+name = "mime_guess"
+version = "2.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4192263c238a5f0d0c6bfd21f336a313a4ce1c450542449ca191bb657b4642ef"
+dependencies = [
+ "mime",
+ "unicase",
+]
+
 [[package]]
 name = "miniz_oxide"
 version = "0.7.1"
@@ -587,6 +597,7 @@ dependencies = [
  "js-sys",
  "log",
  "mime",
+ "mime_guess",
  "native-tls",
  "once_cell",
  "percent-encoding",
@@ -931,6 +942,15 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3528ecfd12c466c6f163363caf2d02a71161dd5e1cc6ae7b34207ea2d42d81ed"
 
+[[package]]
+name = "unicase"
+version = "2.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7d2d4dafb69621809a81864c9c1b864479e1235c0dd4e199924b9742439ed89"
+dependencies = [
+ "version_check",
+]
+
 [[package]]
 name = "unicode-bidi"
 version = "0.3.13"
@@ -970,6 +990,12 @@ version = "0.2.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "accd4ea62f7bb7a82fe23066fb0957d48ef677f6eeb8215f372f52e48bb32426"
 
+[[package]]
+name = "version_check"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
+
 [[package]]
 name = "want"
 version = "0.3.1"
diff --git a/Cargo.toml b/Cargo.toml
index 3186ee2..eb21559 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-reqwest = { version = "0.11.18", features = ["json"] }
+reqwest = { version = "0.11.18", features = ["json", "multipart"] }
 soft_assert = "0.1.1"
 thiserror = "1.0.43"
 tokio = { version = "1.29.1", features = ["net"] }
diff --git a/src/lib.rs b/src/lib.rs
index dea6d44..d133868 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -104,13 +104,13 @@ impl Forgejo {
         self.execute(request).await
     }
 
-    async fn post_form<T: Serialize, U: DeserializeOwned>(
+    async fn post_multipart<T: DeserializeOwned>(
         &self,
         path: &str,
-        body: &T,
-    ) -> Result<U, ForgejoError> {
+        body: reqwest::multipart::Form,
+    ) -> Result<T, ForgejoError> {
         let url = self.url.join("api/v1/").unwrap().join(path).unwrap();
-        let request = self.client.post(url).form(body).build()?;
+        let request = self.client.post(url).multipart(body).build()?;
         self.execute(request).await
     }
 
diff --git a/src/repository.rs b/src/repository.rs
index 4d89ec9..8b063a0 100644
--- a/src/repository.rs
+++ b/src/repository.rs
@@ -140,11 +140,12 @@ impl Forgejo {
         repo: &str,
         id: u64,
         name: &str,
-        file: &[u8],
+        file: Vec<u8>,
     ) -> Result<Attachment, ForgejoError> {
-        self.post_form(
+        self.post_multipart(
             &format!("repos/{owner}/{repo}/releases/{id}/assets?name={name}"),
-            &file,
+            reqwest::multipart::Form::new()
+                .part("attachment", reqwest::multipart::Part::bytes(file).file_name("file").mime_str("*/*").unwrap()),
         )
         .await
     }
diff --git a/tests/ci_test.rs b/tests/ci_test.rs
index 993b8ab..d8a4fa5 100644
--- a/tests/ci_test.rs
+++ b/tests/ci_test.rs
@@ -154,7 +154,7 @@ async fn repo(api: &forgejo_api::Forgejo) -> eyre::Result<()> {
     let release_latest = api.latest_release("TestingAdmin", "test").await.wrap_err("failed to find latest release")?;
     ensure!(release_by_tag == release_latest, "releases not equal");
 
-    let attachment = api.create_release_attachment("TestingAdmin", "test", release.id, "test.txt", b"This is a file!").await.wrap_err("failed to create release attachment")?;
+    let attachment = api.create_release_attachment("TestingAdmin", "test", release.id, "test.txt", b"This is a file!".to_vec()).await.wrap_err("failed to create release attachment")?;
     api.delete_release_attachment("TestingAdmin", "test", release.id, attachment.id).await.wrap_err("failed to deleted attachment")?;
 
     api.delete_release("TestingAdmin", "test", release.id).await.wrap_err("failed to delete release")?;