diff --git a/Cargo.lock b/Cargo.lock
index 81c74d8..71ee6ee 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -80,9 +80,9 @@ checksum = "8aebca1129a03dc6dc2b127edd729435bbc4a37e1d5f4d7513165089ceb02634"
 
 [[package]]
 name = "darling"
-version = "0.10.2"
+version = "0.12.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0d706e75d87e35569db781a9b5e2416cff1236a47ed380831f959382ccd5f858"
+checksum = "a06d4a9551359071d1890820e3571252b91229e0712e7c36b08940e603c5a8fc"
 dependencies = [
  "darling_core",
  "darling_macro",
@@ -90,23 +90,23 @@ dependencies = [
 
 [[package]]
 name = "darling_core"
-version = "0.10.2"
+version = "0.12.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f0c960ae2da4de88a91b2d920c2a7233b400bc33cb28453a2987822d8392519b"
+checksum = "b443e5fb0ddd56e0c9bfa47dc060c5306ee500cb731f2b91432dd65589a77684"
 dependencies = [
  "fnv",
  "ident_case",
  "proc-macro2",
  "quote",
- "strsim 0.9.3",
+ "strsim 0.10.0",
  "syn",
 ]
 
 [[package]]
 name = "darling_macro"
-version = "0.10.2"
+version = "0.12.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d9b5a2f4ac4969822c62224815d069952656cadc7084fdca9751e6d959189b72"
+checksum = "c0220073ce504f12a70efc4e7cdaea9e9b1b324872e7ad96a208056d7a638b81"
 dependencies = [
  "darling_core",
  "quote",
@@ -115,26 +115,33 @@ dependencies = [
 
 [[package]]
 name = "derive_builder"
-version = "0.9.0"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2658621297f2cf68762a6f7dc0bb7e1ff2cfd6583daef8ee0fed6f7ec468ec0"
+checksum = "78ef25735c9f0d0c547d2794701600c94abf030ecb740fad1673fa64461f3573"
+dependencies = [
+ "derive_builder_core",
+ "derive_builder_macro",
+]
+
+[[package]]
+name = "derive_builder_core"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3150f1e84602847b99d3eeb702487fc364f7d6c94f634e944a68fdbaea09e457"
 dependencies = [
  "darling",
- "derive_builder_core",
  "proc-macro2",
  "quote",
  "syn",
 ]
 
 [[package]]
-name = "derive_builder_core"
-version = "0.9.0"
+name = "derive_builder_macro"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2791ea3e372c8495c0bc2033991d76b512cd799d07491fbd6890124db9458bef"
+checksum = "5ca1008bddefdc08d1e734aeb27b94f384390af261b4d1a8fb51fe19c577f05c"
 dependencies = [
- "darling",
- "proc-macro2",
- "quote",
+ "derive_builder_core",
  "syn",
 ]
 
@@ -180,9 +187,9 @@ checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
 
 [[package]]
 name = "libc"
-version = "0.2.88"
+version = "0.2.92"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "03b07a082330a35e43f63177cc01689da34fbffa0105e1246cf0311472cac73a"
+checksum = "56d855069fafbb9b344c0f962150cd2c1187975cb1c22c1522c240d8c4986714"
 
 [[package]]
 name = "mcaptcha-cli"
@@ -200,8 +207,8 @@ checksum = "624a8340c38c1b80fd549087862da4ba43e08858af025b236e509b6649fc13d5"
 
 [[package]]
 name = "pow_sha256"
-version = "0.1.0"
-source = "git+https://github.com/mCaptcha/pow_sha256?tag=0.1.0#0bfbce0185f111b2eb8c14ff74d95dde5af22388"
+version = "0.2.1"
+source = "git+https://github.com/mCaptcha/pow_sha256?tag=0.2.1#df727889c60740bd155d5a06076884636952c66f"
 dependencies = [
  "bincode",
  "derive_builder",
@@ -211,9 +218,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.24"
+version = "1.0.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e0704ee1a7e00d7bb417d0770ea303c1bccbabf0ef1667dae92b5967f5f8a71"
+checksum = "a152013215dca273577e18d2bf00fa862b89b24169fb78c4c95aeb07992c9cec"
 dependencies = [
  "unicode-xid",
 ]
@@ -229,18 +236,18 @@ dependencies = [
 
 [[package]]
 name = "serde"
-version = "1.0.124"
+version = "1.0.125"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bd761ff957cb2a45fbb9ab3da6512de9de55872866160b23c25f1a841e99d29f"
+checksum = "558dc50e1a5a5fa7112ca2ce4effcb321b0300c0d4ccf0776a9f60cd89031171"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.124"
+version = "1.0.125"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1800f7693e94e186f5e25a28291ae1570da908aff7d97a095dec1e56ff99069b"
+checksum = "b093b7a2bb58203b5da3056c05b4ec1fed827dcfdb37347a8841695263b3d06d"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -268,15 +275,15 @@ checksum = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 
 [[package]]
 name = "strsim"
-version = "0.9.3"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6446ced80d6c486436db5c078dde11a9f73d42b57fb273121e160b84f63d894c"
+checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
 [[package]]
 name = "syn"
-version = "1.0.63"
+version = "1.0.68"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8fd9bc7ccc2688b3344c2f48b9b546648b25ce0b20fc717ee7fa7981a8ca9717"
+checksum = "3ce15dd3ed8aa2f8eeac4716d6ef5ab58b6b9256db41d7e1a0224c2788e8fd87"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -294,9 +301,9 @@ dependencies = [
 
 [[package]]
 name = "typenum"
-version = "1.12.0"
+version = "1.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "373c8a200f9e67a0c95e62a4f52fbf80c23b4381c05a17845531982fa99e6b33"
+checksum = "879f6906492a7cd215bfa4cf595b600146ccfac0c79bcbd1f3000162af5e8b06"
 
 [[package]]
 name = "unicode-width"
@@ -318,9 +325,9 @@ checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
 
 [[package]]
 name = "version_check"
-version = "0.9.2"
+version = "0.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b5a972e5669d67ba988ce3dc826706fb0a8b01471c088cb0b6110b805cc36aed"
+checksum = "5fecdca9a5291cc2b8dcf7dc02453fee791a280f3743cb0905f8822ae463b3fe"
 
 [[package]]
 name = "winapi"
diff --git a/Cargo.toml b/Cargo.toml
index 552a5cf..533b1fe 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,5 +6,5 @@ license = "AGPL-3.0"
 edition = "2018"
 
 [dependencies]
-pow_sha256 = { version = "0.1.0", git = "https://github.com/mCaptcha/pow_sha256", tag="0.1.0"}
+pow_sha256 = { version = "0.2.1", git = "https://github.com/mCaptcha/pow_sha256", tag="0.2.1"}
 clap = "2.33"
diff --git a/src/main.rs b/src/main.rs
index 7febc34..d077216 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -33,16 +33,14 @@ fn main() {
         .get_matches();
     let phrase = matches.value_of("phrase").unwrap();
     let salt = matches.value_of("salt").unwrap();
-    let difficulty_factor: u128 = matches
+    let difficulty_factor: u32 = matches
         .value_of("difficulty_factor")
         .unwrap()
         .parse()
         .expect("Please enter an integer for difficulty");
 
     let config = ConfigBuilder::default().salt(salt.into()).build().unwrap();
-
     let work = config.prove_work(&phrase, difficulty_factor).unwrap();
-
     println!("difficulty: {}", &difficulty_factor);
     println!("nonce: {}", &work.nonce);
     println!("original phrase: {}", &phrase);