diff --git a/Cargo.toml b/Cargo.toml
index 4877d9eea2..ca7d392d14 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,9 +9,12 @@ edition = "2018"
 [dev-dependencies]
 criterion = "0.3" # Benchmarking
 
+[features]
+default = ["std"]
+std = []
+
 [dependencies]
 xxhash-rust = { version = "0.8.0-beta.4", features = ["xxh3"] } # xxh3 hashing for rust
-thiserror = "1.0" # A nicer way to write Errors
 hashbrown = "0.9" # A faster hashmap, nostd compatible
 libc = "0.2" # For (*nix) libc
 num = "*"
\ No newline at end of file
diff --git a/src/corpus/mod.rs b/src/corpus/mod.rs
index 6613bce2de..476a825870 100644
--- a/src/corpus/mod.rs
+++ b/src/corpus/mod.rs
@@ -3,9 +3,12 @@ extern crate alloc;
 pub mod testcase;
 pub use testcase::{Testcase, TestcaseMetadata};
 
+use alloc::borrow::ToOwned;
 use alloc::rc::Rc;
+use alloc::vec::Vec;
 use core::cell::RefCell;
 use core::marker::PhantomData;
+#[cfg(feature = "std")]
 use std::path::PathBuf;
 
 use crate::inputs::Input;
@@ -34,16 +37,10 @@ where
     }
 
     /// Add an entry to the corpus
-    #[allow(unused_mut)]
-    fn add(&mut self, mut testcase: Rc<RefCell<Testcase<I>>>) {
+    fn add(&mut self, testcase: Rc<RefCell<Testcase<I>>>) {
         self.entries_mut().push(testcase);
     }
 
-    /// Add an input to the corpus
-    fn add_input(&mut self, input: I) {
-        self.add(Testcase::new(input.into()).into());
-    }
-
     /// Removes an entry from the corpus, returning it if it was present.
     fn remove(&mut self, entry: &Testcase<I>) -> Option<Rc<RefCell<Testcase<I>>>> {
         let mut i: usize = 0;
@@ -135,6 +132,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 pub struct OnDiskCorpus<I, R>
 where
     I: Input,
@@ -145,6 +143,7 @@ where
     dir_path: PathBuf,
 }
 
+#[cfg(feature = "std")]
 impl<I, R> HasEntriesVec<I> for OnDiskCorpus<I, R>
 where
     I: Input,
@@ -158,6 +157,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 impl<I, R> HasRand for OnDiskCorpus<I, R>
 where
     I: Input,
@@ -170,6 +170,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 impl<I, R> Corpus<I> for OnDiskCorpus<I, R>
 where
     I: Input,
@@ -179,9 +180,9 @@ where
     fn add(&mut self, entry: Rc<RefCell<Testcase<I>>>) {
         if *entry.borrow().filename() == None {
             // TODO walk entry metadatas to ask for pices of filename (e.g. :havoc in AFL)
-            let filename = &(String::from("id:") + &self.entries.len().to_string());
-            let filename = self.dir_path.join(filename);
-            *entry.borrow_mut().filename_mut() = Some(filename);
+            let filename = self.dir_path.join(format!("id_{}", &self.entries.len()));
+            let filename_str = filename.to_str().expect("Invalid Path");
+            *entry.borrow_mut().filename_mut() = Some(filename_str.into());
         }
         self.entries.push(entry);
     }
@@ -189,6 +190,7 @@ where
     // TODO save and remove files, cache, etc..., ATM use just InMemoryCorpus
 }
 
+#[cfg(feature = "std")]
 impl<I, R> OnDiskCorpus<I, R>
 where
     I: Input,
@@ -352,6 +354,7 @@ And then:
 */
 
 #[cfg(test)]
+#[cfg(feature = "std")]
 mod tests {
     use crate::corpus::Corpus;
     use crate::corpus::Testcase;
@@ -363,11 +366,11 @@ mod tests {
     use std::path::PathBuf;
 
     #[test]
-
     fn test_queuecorpus() {
-        let rand: Rc<_> = DefaultRand::preseeded().into();
+        let rand: Rc<_> = DefaultRand::new(0).into();
         let mut q = QueueCorpus::new(OnDiskCorpus::new(&rand, PathBuf::from("fancy/path")));
-        let t: Rc<_> = Testcase::with_filename(BytesInput::new(vec![0 as u8; 4]), PathBuf::from("fancyfile")).into();
+        let t: Rc<_> =
+            Testcase::with_filename(BytesInput::new(vec![0 as u8; 4]), "fancyfile".into()).into();
         q.add(t);
         let filename = q
             .next()
@@ -387,6 +390,6 @@ mod tests {
                 .unwrap()
                 .to_owned()
         );
-        assert_eq!(filename, PathBuf::from("fancyfile"));
+        assert_eq!(filename, "fancyfile");
     }
 }
diff --git a/src/corpus/testcase.rs b/src/corpus/testcase.rs
index e2441bf3e5..cc689e9465 100644
--- a/src/corpus/testcase.rs
+++ b/src/corpus/testcase.rs
@@ -7,9 +7,12 @@ use alloc::rc::Rc;
 use core::cell::RefCell;
 use core::convert::Into;
 use hashbrown::HashMap;
+#[cfg(feature = "std")]
 use std::fs::File;
+#[cfg(feature = "std")]
 use std::io::Write;
-use std::path::{Path, PathBuf};
+#[cfg(feature = "std")]
+use std::path::Path;
 
 // TODO: Give example
 /// Metadata for a testcase
@@ -18,6 +21,24 @@ pub trait TestcaseMetadata {
     fn name(&self) -> &'static str;
 }
 
+/*
+pub trait Testcase<I, T>
+where
+    I: Input,
+    T: TestcaseMetadata,
+{
+
+    fn input(&mut self) -> Option<I>
+
+    input: Option<I>,
+    /// Filename, if this testcase is backed by a file in the filesystem
+    filename: Option<String>,
+    /// Map of metadatas associated with this testcase
+    metadatas: HashMap<&'static str, Box<dyn TestcaseMetadata>>,
+
+}
+*/
+
 pub enum FileBackedTestcase<I, P> {
     /// A testcase on disk, not yet loaded
     Stored { filename: P },
@@ -109,7 +130,7 @@ where
     /// The input of this testcase
     input: Option<I>,
     /// Filename, if this testcase is backed by a file in the filesystem
-    filename: Option<PathBuf>,
+    filename: Option<String>,
     /// Map of metadatas associated with this testcase
     metadatas: HashMap<&'static str, Box<dyn TestcaseMetadata>>,
 }
@@ -133,7 +154,7 @@ where
         // TODO: Implement cache to disk
         match self.input.as_ref() {
             Some(i) => Ok(i),
-            None => Err(AflError::NotImplemented("load_input".to_string())),
+            None => Err(AflError::NotImplemented("load_input".into())),
         }
     }
 
@@ -151,15 +172,15 @@ where
     }
 
     /// Get the filename, if any
-    pub fn filename(&self) -> &Option<PathBuf> {
+    pub fn filename(&self) -> &Option<String> {
         &self.filename
     }
     /// Get the filename, if any (mutable)
-    pub fn filename_mut(&mut self) -> &mut Option<PathBuf> {
+    pub fn filename_mut(&mut self) -> &mut Option<String> {
         &mut self.filename
     }
     /// Set the filename
-    pub fn set_filename(&mut self, filename: Option<PathBuf>) {
+    pub fn set_filename(&mut self, filename: Option<String>) {
         self.filename = filename;
     }
 
@@ -183,7 +204,7 @@ where
     }
 
     /// Create a new Testcase instace given an input and a filename
-    pub fn with_filename(input: I, filename: PathBuf) -> Self {
+    pub fn with_filename(input: I, filename: String) -> Self {
         Testcase {
             input: Some(input),
             filename: Some(filename),
diff --git a/src/engines/mod.rs b/src/engines/mod.rs
index ade29f6392..c42126af47 100644
--- a/src/engines/mod.rs
+++ b/src/engines/mod.rs
@@ -103,7 +103,7 @@ mod tests {
 
     #[test]
     fn test_engine() {
-        let rand: Rc<_> = DefaultRand::preseeded().into();
+        let rand: Rc<_> = DefaultRand::new(0).into();
 
         let mut corpus = InMemoryCorpus::<BytesInput, _>::new(&rand);
         let testcase = Testcase::new(BytesInput::new(vec![0; 4])).into();
diff --git a/src/executors/inmemory.rs b/src/executors/inmemory.rs
index 807611b081..bf3c590f31 100644
--- a/src/executors/inmemory.rs
+++ b/src/executors/inmemory.rs
@@ -67,11 +67,11 @@ where
         self.observers.push(observer);
     }
 
-    fn observers(&self) -> &Vec<Box<dyn Observer>> {
+    fn observers(&self) -> &[Box<dyn Observer>] {
         &self.observers
     }
 
-    fn feedbacks(&self) -> &Vec<Box<dyn Feedback<I>>> {
+    fn feedbacks(&self) -> &[Box<dyn Feedback<I>>] {
         &self.feedbacks
     }
 
@@ -211,10 +211,10 @@ mod tests {
 
     impl Observer for Nopserver {
         fn reset(&mut self) -> Result<(), AflError> {
-            Err(AflError::Unknown("Nop reset, testing only".to_string()))
+            Err(AflError::Unknown("Nop reset, testing only".into()))
         }
         fn post_exec(&mut self) -> Result<(), AflError> {
-            Err(AflError::Unknown("Nop exec, testing only".to_string()))
+            Err(AflError::Unknown("Nop exec, testing only".into()))
         }
     }
 
diff --git a/src/executors/mod.rs b/src/executors/mod.rs
index af918a17c1..a539acd372 100644
--- a/src/executors/mod.rs
+++ b/src/executors/mod.rs
@@ -1,10 +1,6 @@
 extern crate alloc;
 pub mod inmemory;
 
-use alloc::rc::Rc;
-use core::cell::RefCell;
-
-use crate::corpus::Testcase;
 use crate::corpus::TestcaseMetadata;
 use crate::feedbacks::Feedback;
 use crate::inputs::Input;
@@ -37,13 +33,13 @@ where
     fn add_observer(&mut self, observer: Box<dyn Observer>);
 
     /// Get the linked observers
-    fn observers(&self) -> &Vec<Box<dyn Observer>>;
+    fn observers(&self) -> &[Box<dyn Observer>];
 
     /// Adds a feedback
     fn add_feedback(&mut self, feedback: Box<dyn Feedback<I>>);
 
     /// Returns vector of feebacks
-    fn feedbacks(&self) -> &Vec<Box<dyn Feedback<I>>>;
+    fn feedbacks(&self) -> &[Box<dyn Feedback<I>>];
 
     /// Returns vector of feebacks (mutable)
     fn feedbacks_mut(&mut self) -> &mut Vec<Box<dyn Feedback<I>>>;
@@ -66,12 +62,6 @@ where
         }
 
         if rate_acc >= 25 {
-            let new_entry = Rc::new(RefCell::new(Testcase::<I>::new(input.clone())));
-            for meta in metadatas {
-                new_entry.borrow_mut().add_metadata(meta);
-            }
-            //TODO corpus.add(new_entry);
-
             Ok(true)
         } else {
             Ok(false)
diff --git a/src/feedbacks/mod.rs b/src/feedbacks/mod.rs
index 3d5744ca37..33d3395550 100644
--- a/src/feedbacks/mod.rs
+++ b/src/feedbacks/mod.rs
@@ -3,6 +3,8 @@ extern crate num;
 
 use core::cell::RefCell;
 use core::marker::PhantomData;
+
+use alloc::vec::*;
 use num::Integer;
 
 use crate::corpus::TestcaseMetadata;
diff --git a/src/inputs/bytes.rs b/src/inputs/bytes.rs
index 4150a55b50..f518c98099 100644
--- a/src/inputs/bytes.rs
+++ b/src/inputs/bytes.rs
@@ -1,9 +1,10 @@
 extern crate alloc;
 
-use core::convert::From;
-
+use alloc::borrow::ToOwned;
 use alloc::rc::Rc;
+use alloc::vec::Vec;
 use core::cell::RefCell;
+use core::convert::From;
 
 use crate::inputs::{HasBytesVec, HasTargetBytes, Input};
 use crate::AflError;
@@ -20,7 +21,9 @@ impl Input for BytesInput {
     }
 
     fn deserialize(buf: &[u8]) -> Result<Self, AflError> {
-        Ok(Self { bytes: buf.into() })
+        Ok(Self {
+            bytes: buf.to_owned(),
+        })
     }
 }
 
@@ -32,7 +35,7 @@ impl Into<Rc<RefCell<Self>>> for BytesInput {
 }
 
 impl HasBytesVec for BytesInput {
-    fn bytes(&self) -> &Vec<u8> {
+    fn bytes(&self) -> &[u8] {
         &self.bytes
     }
     fn bytes_mut(&mut self) -> &mut Vec<u8> {
@@ -41,7 +44,7 @@ impl HasBytesVec for BytesInput {
 }
 
 impl HasTargetBytes for BytesInput {
-    fn target_bytes(&self) -> &Vec<u8> {
+    fn target_bytes(&self) -> &[u8] {
         &self.bytes
     }
 }
@@ -71,7 +74,7 @@ mod tests {
 
     #[test]
     fn test_input() {
-        let mut rand = DefaultRand::preseeded();
+        let mut rand = DefaultRand::new(0);
         assert_ne!(rand.next(), rand.next());
         assert!(rand.below(100) < 100);
         assert_eq!(rand.below(1), 0);
diff --git a/src/inputs/mod.rs b/src/inputs/mod.rs
index fa894fbe46..f291264ac2 100644
--- a/src/inputs/mod.rs
+++ b/src/inputs/mod.rs
@@ -3,15 +3,21 @@ extern crate alloc;
 pub mod bytes;
 pub use bytes::BytesInput;
 
+use alloc::vec::Vec;
 use core::clone::Clone;
-use std::io::Write;
+
+#[cfg(feature = "std")]
+use std::fs::File;
+#[cfg(feature = "std")]
+use std::io::{Read, Write};
+#[cfg(feature = "std")]
 use std::path::Path;
-use std::{fs::File, io::Read};
 
 use crate::AflError;
 
 /// An input for the target
 pub trait Input: Clone {
+    #[cfg(feature = "std")]
     /// Write this input to the file
     fn to_file<P>(&self, path: P) -> Result<(), AflError>
     where
@@ -22,7 +28,15 @@ pub trait Input: Clone {
         Ok(())
     }
 
+    #[cfg(not(feature = "std"))]
+    /// Write this input to the file
+    fn to_file<P>(&self, string: P) -> Result<(), AflError>
+where {
+        Err(AflError::NotImplemented("Not suppored in no_std".into()))
+    }
+
     /// Load the contents of this input from a file
+    #[cfg(feature = "std")]
     fn from_file<P>(path: P) -> Result<Self, AflError>
     where
         P: AsRef<Path>,
@@ -33,6 +47,13 @@ pub trait Input: Clone {
         Self::deserialize(&bytes)
     }
 
+    /// Write this input to the file
+    #[cfg(not(feature = "std"))]
+    fn from_file<P>(string: P) -> Result<Self, AflError>
+where {
+        Err(AflError::NotImplemented("Not suppored in no_std".into()))
+    }
+
     /// Serialize this input, for later deserialization.
     /// This is not necessarily the representation to be used by the target
     /// Instead, to get bytes for a target, use [HasTargetBytes](afl::inputs::HasTargetBytes).
@@ -47,13 +68,13 @@ pub trait Input: Clone {
 /// Instead, it can be used as bytes input for a target
 pub trait HasTargetBytes {
     /// Target bytes, that can be written to a target
-    fn target_bytes(&self) -> &Vec<u8>;
+    fn target_bytes(&self) -> &[u8];
 }
 
 /// Contains an internal bytes Vector
 pub trait HasBytesVec {
     /// The internal bytes map
-    fn bytes(&self) -> &Vec<u8>;
+    fn bytes(&self) -> &[u8];
     /// The internal bytes map (as mutable borrow)
     fn bytes_mut(&mut self) -> &mut Vec<u8>;
 }
diff --git a/src/lib.rs b/src/lib.rs
index 24f81c932a..af0253b448 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,5 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+#[macro_use]
 extern crate alloc;
 
 pub mod corpus;
@@ -11,32 +13,52 @@ pub mod observers;
 pub mod stages;
 pub mod utils;
 
+use alloc::string::String;
+use core::fmt;
+#[cfg(feature = "std")]
 use std::io;
-use thiserror::Error;
 
 /// Main error struct for AFL
-#[derive(Error, Debug)]
+#[derive(Debug)]
 pub enum AflError {
-    #[error("Error in Serialization: `{0}`")]
     Serialize(String),
-    #[error("File IO failed")]
-    File(#[from] io::Error),
-    #[error("Optional value `{0}` was not set")]
+    #[cfg(feature = "std")]
+    File(io::Error),
     EmptyOptional(String),
-    #[error("Key `{0}` not in Corpus")]
     KeyNotFound(String),
-    #[error("No items in {0}")]
     Empty(String),
-    #[error("All elements have been processed in {0} iterator")]
     IteratorEnd(String),
-    #[error("Not implemented: {0}")]
     NotImplemented(String),
-    #[error("Illegal state: {0}")]
     IllegalState(String),
-    #[error("Unknown error: {0}")]
     Unknown(String),
 }
 
+impl fmt::Display for AflError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::Serialize(s) => write!(f, "Error in Serialization: `{0}`", &s),
+            #[cfg(feature = "std")]
+            Self::File(err) => write!(f, "File IO failed: {:?}", &err),
+            Self::EmptyOptional(s) => write!(f, "Optional value `{0}` was not set", &s),
+            Self::KeyNotFound(s) => write!(f, "Key `{0}` not in Corpus", &s),
+            Self::Empty(s) => write!(f, "No items in {0}", &s),
+            Self::IteratorEnd(s) => {
+                write!(f, "All elements have been processed in {0} iterator", &s)
+            }
+            Self::NotImplemented(s) => write!(f, "Not implemented: {0}", &s),
+            Self::IllegalState(s) => write!(f, "Illegal state: {0}", &s),
+            Self::Unknown(s) => write!(f, "Unknown error: {0}", &s),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl From<io::Error> for AflError {
+    fn from(err: io::Error) -> Self {
+        Self::File(err)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     #[test]
diff --git a/src/mutators/scheduled.rs b/src/mutators/scheduled.rs
index ae78b39387..ed7bfe6e6d 100644
--- a/src/mutators/scheduled.rs
+++ b/src/mutators/scheduled.rs
@@ -7,6 +7,7 @@ use crate::utils::{HasRand, Rand};
 use crate::AflError;
 
 use alloc::rc::Rc;
+use alloc::vec::Vec;
 use core::cell::RefCell;
 use core::marker::PhantomData;
 
@@ -42,7 +43,7 @@ where
     fn schedule(&mut self, _input: &I) -> Result<MutationFunction<C, Self, I>, AflError> {
         let count = self.mutations_count() as u64;
         if count == 0 {
-            return Err(AflError::Empty("no mutations".to_string()));
+            return Err(AflError::Empty("no mutations".into()));
         }
         let idx;
         {
@@ -109,7 +110,7 @@ where
 {
     fn mutation_by_idx(&self, index: usize) -> Result<MutationFunction<C, Self, I>, AflError> {
         if index >= self.mutations.len() {
-            return Err(AflError::Unknown("oob".to_string()));
+            return Err(AflError::Unknown("oob".into()));
         }
         Ok(self.mutations[index])
     }
@@ -172,7 +173,7 @@ where
 }
 
 /// Returns the first and last diff position between the given vectors, stopping at the min len
-fn locate_diffs(this: &Vec<u8>, other: &Vec<u8>) -> (i64, i64) {
+fn locate_diffs(this: &[u8], other: &[u8]) -> (i64, i64) {
     let mut first_diff: i64 = -1;
     let mut last_diff: i64 = -1;
     for (i, (this_el, other_el)) in this.iter().zip(other.iter()).enumerate() {
@@ -208,7 +209,7 @@ where
             Err(_) => {
                 if retry_count == 20 {
                     return Err(AflError::Empty(
-                        "No suitable testcase found for splicing".to_owned(),
+                        "No suitable testcase found for splicing".into(),
                     ));
                 }
                 retry_count += 1;
@@ -231,7 +232,7 @@ where
             break (f, l);
         }
         if counter == 20 {
-            return Err(AflError::Empty("No valid diff found".to_owned()));
+            return Err(AflError::Empty("No valid diff found".into()));
         }
         counter += 1;
     };
@@ -324,10 +325,13 @@ where
 
 #[cfg(test)]
 mod tests {
-    use crate::corpus::{Corpus, InMemoryCorpus};
-    use crate::inputs::{BytesInput, HasBytesVec};
+    use crate::inputs::BytesInput;
     use crate::mutators::scheduled::mutation_splice;
     use crate::utils::{DefaultHasRand, Rand, XKCDRand};
+    use crate::{
+        corpus::{Corpus, InMemoryCorpus, Testcase},
+        inputs::HasBytesVec,
+    };
     use alloc::rc::Rc;
 
     #[test]
@@ -336,8 +340,8 @@ mod tests {
         let rand: Rc<_> = XKCDRand::new().into();
         let mut has_rand = DefaultHasRand::new(&rand);
         let mut corpus = InMemoryCorpus::new(&rand);
-        corpus.add_input(BytesInput::new(vec!['a' as u8, 'b' as u8, 'c' as u8]));
-        corpus.add_input(BytesInput::new(vec!['d' as u8, 'e' as u8, 'f' as u8]));
+        corpus.add(Testcase::new(BytesInput::new(vec!['a' as u8, 'b' as u8, 'c' as u8])).into());
+        corpus.add(Testcase::new(BytesInput::new(vec!['d' as u8, 'e' as u8, 'f' as u8])).into());
 
         let testcase_rr = corpus.next().expect("Corpus did not contain entries");
         let mut testcase = testcase_rr.borrow_mut();
@@ -346,10 +350,11 @@ mod tests {
         rand.borrow_mut().set_seed(5);
         mutation_splice(&mut has_rand, &mut corpus, &mut input).unwrap();
 
+        #[cfg(feature = "std")]
         println!("{:?}", input.bytes());
 
         // The pre-seeded rand should have spliced at position 2.
         // TODO: Maybe have a fixed rand for this purpose?
-        assert_eq!(input.bytes(), &vec!['a' as u8, 'b' as u8, 'f' as u8])
+        assert_eq!(input.bytes(), &['a' as u8, 'b' as u8, 'f' as u8])
     }
 }
diff --git a/src/utils.rs b/src/utils.rs
index 21d383e6af..553664c13f 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -5,9 +5,11 @@ use alloc::rc::Rc;
 use core::cell::RefCell;
 use core::debug_assert;
 use core::fmt::Debug;
-use std::time::{SystemTime, UNIX_EPOCH};
 use xxhash_rust::xxh3::xxh3_64_with_seed;
 
+#[cfg(feature = "std")]
+use std::time::{SystemTime, UNIX_EPOCH};
+
 pub type DefaultRand = Xoshiro256StarRand;
 
 /// Ways to get random around here
@@ -128,6 +130,8 @@ impl Xoshiro256StarRand {
     }
 
     /// Creates a rand instance, pre-seeded with the current time in nanoseconds.
+    /// Needs stdlib timer
+    #[cfg(feature = "std")]
     pub fn preseeded() -> Self {
         let seed = SystemTime::now()
             .duration_since(UNIX_EPOCH)
@@ -220,7 +224,7 @@ mod tests {
 
     #[test]
     fn test_rand() {
-        let mut rand = DefaultRand::preseeded();
+        let mut rand = DefaultRand::new(0);
         assert_ne!(rand.next(), rand.next());
         assert!(rand.below(100) < 100);
         assert_eq!(rand.below(1), 0);
@@ -230,7 +234,7 @@ mod tests {
 
     #[test]
     fn test_has_rand() {
-        let rand = DefaultRand::preseeded().into();
+        let rand = DefaultRand::new(0).into();
         let has_rand = DefaultHasRand::new(&rand);
 
         assert!(has_rand.rand_below(100) < 100);