diff --git a/Cargo.toml b/Cargo.toml
index 3c42f202..310b687a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,14 +3,11 @@ name = "cashu-rs"
 version = "0.1.0"
 edition = "2021"
 
-[workspace]
-members = ["integration_test"]
-
-
 [dependencies]
 bitcoin = { version = "0.30.0", features=["serde"] }
 lightning-invoice = { version = "0.22.0", features=["serde"] }
 minreq = { version = "2.7.0", features = ["json-using-serde", "https"] }
+secp256k1 = "0.27.0"
 serde = { version = "1.0.160", features = ["derive"]}
 thiserror = "1.0.40"
 url = "2.3.1"
diff --git a/src/cashu_mint.rs b/src/cashu_mint.rs
index abb584f8..5881a2e6 100644
--- a/src/cashu_mint.rs
+++ b/src/cashu_mint.rs
@@ -1,3 +1,4 @@
+use bitcoin::Amount;
 use lightning_invoice::Invoice;
 use url::Url;
 
@@ -32,10 +33,11 @@ impl CashuMint {
     }
 
     /// Request Mint [NUT-03]
-    pub async fn request_mint(&self, amount: u64) -> Result<RequestMintResponse, Error> {
+    pub async fn request_mint(&self, amount: Amount) -> Result<RequestMintResponse, Error> {
         let mut url = self.url.join("mint")?;
         url.query_pairs_mut()
-            .append_pair("amount", &amount.to_string());
+            .append_pair("amount", &amount.to_sat().to_string());
+        println!("{url}");
 
         Ok(minreq::get(url).send()?.json::<RequestMintResponse>()?)
     }
@@ -97,7 +99,7 @@ impl CashuMint {
     /// Split Token [NUT-06]
     pub async fn split(
         &self,
-        amount: u64,
+        amount: Amount,
         proofs: Vec<Proof>,
         outputs: Vec<BlindedMessage>,
     ) -> Result<SplitResponse, Error> {
diff --git a/src/dhke.rs b/src/dhke.rs
new file mode 100644
index 00000000..4c2a4586
--- /dev/null
+++ b/src/dhke.rs
@@ -0,0 +1 @@
+//! Diffie-Hellmann key exchange
diff --git a/src/types.rs b/src/types.rs
index 346168fa..6c6ce3f5 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -10,7 +10,8 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct BlindedMessage {
     /// Amount in satoshi
-    pub amount: u64,
+    #[serde(with = "bitcoin::amount::serde::as_sat")]
+    pub amount: Amount,
     /// encrypted secret message (B_)
     #[serde(rename = "B_")]
     pub b: String,
@@ -31,7 +32,8 @@ pub struct Promise {
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct Proof {
     /// Amount in satoshi
-    pub amount: u64,
+    #[serde(with = "bitcoin::amount::serde::as_sat")]
+    pub amount: Amount,
     /// Secret message
     pub secret: String,
     /// Unblinded signature
@@ -78,8 +80,9 @@ pub struct PostMintResponse {
 /// Check Fees Response [NUT-05]
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct CheckFeesResponse {
-    /// Expected Mac Fee in satoshis
-    pub fee: u64,
+    /// Expected Mac Fee in satoshis    
+    #[serde(with = "bitcoin::amount::serde::as_sat")]
+    pub fee: Amount,
 }
 
 /// Check Fees request [NUT-05]
@@ -112,7 +115,8 @@ pub struct MeltResposne {
 /// Split Request [NUT-06]
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct SplitRequest {
-    pub amount: u64,
+    #[serde(with = "bitcoin::amount::serde::as_sat")]
+    pub amount: Amount,
     pub proofs: Vec<Proof>,
     pub outputs: Vec<BlindedMessage>,
 }
@@ -163,7 +167,7 @@ impl<'de> Deserialize<'de> for MintVersion {
         D: Deserializer<'de>,
     {
         let combined = String::deserialize(deserializer)?;
-        let parts: Vec<&str> = combined.split(" / ").collect();
+        let parts: Vec<&str> = combined.split('/').collect();
         if parts.len() != 2 {
             return Err(serde::de::Error::custom("Invalid input string"));
         }
diff --git a/tests/integration_test.rs b/tests/integration_test.rs
index fedeb5d2..18945312 100644
--- a/tests/integration_test.rs
+++ b/tests/integration_test.rs
@@ -1,20 +1,13 @@
 use std::str::FromStr;
 
+use bitcoin::Amount;
+use lightning_invoice::Invoice;
 use url::Url;
 
 use cashu_rs::cashu_mint::CashuMint;
 
 const MINTURL: &str = "https://legend.lnbits.com/cashu/api/v1/SKvHRus9dmjWHhstHrsazW/";
 
-#[ignore]
-#[tokio::test]
-async fn test_get_mint_info() {
-    let url = Url::from_str(MINTURL).unwrap();
-    let mint = CashuMint::new(url);
-    let mint_info = mint.get_info().await.unwrap();
-    // println!("{:?}", mint_info);
-}
-
 #[tokio::test]
 async fn test_get_mint_keys() {
     let url = Url::from_str(MINTURL).unwrap();
@@ -32,3 +25,34 @@ async fn test_get_mint_keysets() {
 
     assert!(!mint_keysets.keysets.is_empty())
 }
+
+#[tokio::test]
+async fn test_request_mint() {
+    let url = Url::from_str(MINTURL).unwrap();
+    let mint = CashuMint::new(url);
+
+    let mint = mint.request_mint(Amount::from_sat(21)).await.unwrap();
+
+    assert!(mint.pr.check_signature().is_ok())
+}
+
+#[tokio::test]
+async fn test_check_fees() {
+    let invoice = Invoice::from_str("lnbc10n1p3a6s0dsp5n55r506t2fv4r0mjcg30v569nk2u9s40ur4v3r3mgtscjvkvnrqqpp5lzfv8fmjzduelk74y9rsrxrayvhyzcdsh3zkdgv0g50napzalvqsdqhf9h8vmmfvdjn5gp58qengdqxq8p3aaymdcqpjrzjqwryaup9lh50kkranzgcdnn2fgvx390wgj5jd07rwr3vxeje0glc7z70cgqqg4sqqqqqqqlgqqqqrucqjq9qyysgqrjky5axsldzhqsjwsc38xa37k6t04le3ws4t26nqej62vst5xkz56qw85r6c4a3tr79588e0ceuuahwgfnkqc6n6269unlwqtvwr5vqqy0ncdq").unwrap();
+
+    let url = Url::from_str(MINTURL).unwrap();
+    let mint = CashuMint::new(url);
+
+    let fee = mint.check_fees(invoice).await.unwrap();
+    println!("{fee:?}");
+}
+
+#[ignore]
+#[tokio::test]
+async fn test_get_mint_info() {
+    let url = Url::from_str(MINTURL).unwrap();
+    let mint = CashuMint::new(url);
+    let mint_info = mint.get_info().await.unwrap();
+
+    // println!("{:?}", mint_info);
+}