diff --git a/afl/src/corpus/mod.rs b/afl/src/corpus/mod.rs
index d92ab7e347..e260379b4a 100644
--- a/afl/src/corpus/mod.rs
+++ b/afl/src/corpus/mod.rs
@@ -4,6 +4,7 @@ pub use testcase::{Testcase, TestcaseMetadata};
 use alloc::borrow::ToOwned;
 use alloc::vec::Vec;
 use core::marker::PhantomData;
+use core::cell::RefCell;
 use core::ptr;
 
 #[cfg(feature = "std")]
@@ -18,10 +19,10 @@ where
     I: Input,
 {
     /// Get the entries vector field
-    fn entries(&self) -> &[Testcase<I>];
+    fn entries(&self) -> &[RefCell<Testcase<I>>];
 
     /// Get the entries vector field (mutable)
-    fn entries_mut(&mut self) -> &mut Vec<Testcase<I>>;
+    fn entries_mut(&mut self) -> &mut Vec<RefCell<Testcase<I>>>;
 }
 
 /// Corpus with all current testcases
@@ -37,7 +38,7 @@ where
 
     /// Add an entry to the corpus and return its index
     fn add(&mut self, testcase: Testcase<I>) -> usize {
-        self.entries_mut().push(testcase);
+        self.entries_mut().push(RefCell::new(testcase));
         self.entries().len() - 1
     }
 
@@ -49,25 +50,25 @@ where
                 idx
             )));
         }
-        self.entries_mut()[idx] = testcase;
+        self.entries_mut()[idx] = RefCell::new(testcase);
         Ok(())
     }
 
     /// Get by id
-    fn get(&self, idx: usize) -> &Testcase<I> {
+    fn get(&self, idx: usize) -> &RefCell<Testcase<I>> {
         &self.entries()[idx]
     }
 
     /// Removes an entry from the corpus, returning it if it was present.
     fn remove(&mut self, entry: &Testcase<I>) -> Option<Testcase<I>> {
-        match self.entries().iter().position(|x| ptr::eq(x, entry)) {
-            Some(i) => Some(self.entries_mut().remove(i)),
+        match self.entries().iter().position(|x| ptr::eq(x.as_ptr(), entry)) {
+            Some(i) => Some(self.entries_mut().remove(i).into_inner()),
             None => None,
         }
     }
 
     /// Gets a random entry
-    fn random_entry(&self, rand: &mut R) -> Result<(&Testcase<I>, usize), AflError> {
+    fn random_entry(&self, rand: &mut R) -> Result<(&RefCell<Testcase<I>>, usize), AflError> {
         if self.count() == 0 {
             Err(AflError::Empty("No entries in corpus".to_owned()))
         } else {
@@ -78,7 +79,7 @@ where
     }
 
     /// Returns the testcase for the given idx, with loaded input
-    fn load_testcase(&mut self, idx: usize) -> Result<(), AflError> {
+    /*fn load_testcase(&mut self, idx: usize) -> Result<(), AflError> {
         let testcase = self.get(idx);
         // Ensure testcase is loaded
         match testcase.input() {
@@ -97,14 +98,14 @@ where
             _ => (),
         }
         Ok(())
-    }
+    }*/
 
     // TODO: IntoIter
     /// Gets the next entry
-    fn next(&mut self, rand: &mut R) -> Result<(&Testcase<I>, usize), AflError>;
+    fn next(&mut self, rand: &mut R) -> Result<(&RefCell<Testcase<I>>, usize), AflError>;
 
     /// Returns the testacase we currently use
-    fn current_testcase(&self) -> (&Testcase<I>, usize);
+    fn current_testcase(&self) -> (&RefCell<Testcase<I>>, usize);
 }
 
 pub struct InMemoryCorpus<I, R>
@@ -112,7 +113,7 @@ where
     I: Input,
     R: Rand,
 {
-    entries: Vec<Testcase<I>>,
+    entries: Vec<RefCell<Testcase<I>>>,
     pos: usize,
     phantom: PhantomData<R>,
 }
@@ -122,10 +123,10 @@ where
     I: Input,
     R: Rand,
 {
-    fn entries(&self) -> &[Testcase<I>] {
+    fn entries(&self) -> &[RefCell<Testcase<I>>] {
         &self.entries
     }
-    fn entries_mut(&mut self) -> &mut Vec<Testcase<I>> {
+    fn entries_mut(&mut self) -> &mut Vec<RefCell<Testcase<I>>> {
         &mut self.entries
     }
 }
@@ -136,7 +137,7 @@ where
     R: Rand,
 {
     /// Gets the next entry
-    fn next(&mut self, rand: &mut R) -> Result<(&Testcase<I>, usize), AflError> {
+    fn next(&mut self, rand: &mut R) -> Result<(&RefCell<Testcase<I>>, usize), AflError> {
         if self.count() == 0 {
             Err(AflError::Empty("No entries in corpus".to_owned()))
         } else {
@@ -148,7 +149,7 @@ where
     }
 
     /// Returns the testacase we currently use
-    fn current_testcase(&self) -> (&Testcase<I>, usize) {
+    fn current_testcase(&self) -> (&RefCell<Testcase<I>>, usize) {
         (self.get(self.pos), self.pos)
     }
 }
@@ -173,7 +174,7 @@ where
     I: Input,
     R: Rand,
 {
-    entries: Vec<Testcase<I>>,
+    entries: Vec<RefCell<Testcase<I>>>,
     dir_path: PathBuf,
     pos: usize,
     phantom: PhantomData<R>,
@@ -185,10 +186,10 @@ where
     I: Input,
     R: Rand,
 {
-    fn entries(&self) -> &[Testcase<I>] {
+    fn entries(&self) -> &[RefCell<Testcase<I>>] {
         &self.entries
     }
-    fn entries_mut(&mut self) -> &mut Vec<Testcase<I>> {
+    fn entries_mut(&mut self) -> &mut Vec<RefCell<Testcase<I>>> {
         &mut self.entries
     }
 }
@@ -210,16 +211,16 @@ where
             }
             _ => {}
         }
-        self.entries.push(entry);
+        self.entries.push(RefCell::new(entry));
         self.entries.len() - 1
     }
 
-    fn current_testcase(&self) -> (&Testcase<I>, usize) {
+    fn current_testcase(&self) -> (&RefCell<Testcase<I>>, usize) {
         (self.get(self.pos), self.pos)
     }
 
     /// Gets the next entry
-    fn next(&mut self, rand: &mut R) -> Result<(&Testcase<I>, usize), AflError> {
+    fn next(&mut self, rand: &mut R) -> Result<(&RefCell<Testcase<I>>, usize), AflError> {
         if self.count() == 0 {
             Err(AflError::Empty("No entries in corpus".to_owned()))
         } else {
@@ -268,10 +269,10 @@ where
     I: Input,
     R: Rand,
 {
-    fn entries(&self) -> &[Testcase<I>] {
+    fn entries(&self) -> &[RefCell<Testcase<I>>] {
         self.corpus.entries()
     }
-    fn entries_mut(&mut self) -> &mut Vec<Testcase<I>> {
+    fn entries_mut(&mut self) -> &mut Vec<RefCell<Testcase<I>>> {
         self.corpus.entries_mut()
     }
 }
@@ -297,17 +298,17 @@ where
     }
 
     /// Gets a random entry
-    fn random_entry(&self, rand: &mut R) -> Result<(&Testcase<I>, usize), AflError> {
+    fn random_entry(&self, rand: &mut R) -> Result<(&RefCell<Testcase<I>>, usize), AflError> {
         self.corpus.random_entry(rand)
     }
 
     /// Returns the testacase we currently use
-    fn current_testcase(&self) -> (&Testcase<I>, usize) {
+    fn current_testcase(&self) -> (&RefCell<Testcase<I>>, usize) {
         (self.get(self.pos - 1), self.pos - 1)
     }
 
     /// Gets the next entry
-    fn next(&mut self, _rand: &mut R) -> Result<(&Testcase<I>, usize), AflError> {
+    fn next(&mut self, _rand: &mut R) -> Result<(&RefCell<Testcase<I>>, usize), AflError> {
         self.pos += 1;
         if self.corpus.count() == 0 {
             return Err(AflError::Empty("Corpus".to_owned()));
@@ -417,6 +418,7 @@ mod tests {
             .next(&mut rand)
             .unwrap()
             .0
+            .borrow()
             .filename()
             .as_ref()
             .unwrap()
@@ -426,6 +428,7 @@ mod tests {
             q.next(&mut rand)
                 .unwrap()
                 .0
+                .borrow()
                 .filename()
                 .as_ref()
                 .unwrap()
diff --git a/afl/src/corpus/testcase.rs b/afl/src/corpus/testcase.rs
index daca24ef74..a30d45e262 100644
--- a/afl/src/corpus/testcase.rs
+++ b/afl/src/corpus/testcase.rs
@@ -75,9 +75,11 @@ where
     I: Input,
 {
     /// Returns this testcase with a loaded input
-    pub fn load_from_disk(filename: &str) -> Result<Self, AflError> {
-        let input = I::from_file(filename)?;
-        Ok(Testcase::new(input))
+    pub fn load_input(&mut self) -> Result<&I, AflError> {
+        if self.input.is_none() {
+            self.input = Some(I::from_file(self.filename.as_ref().unwrap())?);
+        }
+        Ok(self.input.as_ref().unwrap())
     }
 
     /// Get the input, if any
diff --git a/afl/src/engines/mod.rs b/afl/src/engines/mod.rs
index 4545fc5329..1e4542d36c 100644
--- a/afl/src/engines/mod.rs
+++ b/afl/src/engines/mod.rs
@@ -293,19 +293,10 @@ where
         corpus: &mut C,
         engine: &mut Engine<EM, E, C, I, R>,
     ) -> Result<usize, AflError> {
-        let (testcase, idx) = corpus.next(rand)?;
-        match testcase.input() {
-            None => {
-                // Load from disk.
-                corpus.load_testcase(idx)?;
-            }
-            _ => (),
-        };
-
-        let input = corpus.get(idx).input().as_ref().unwrap();
+        let (_, idx) = corpus.next(rand)?;
 
         for stage in self.stages_mut() {
-            stage.perform(rand, state, corpus, engine, &input)?;
+            stage.perform(rand, state, corpus, engine, idx)?;
         }
 
         engine.events_manager_mut().process(state, corpus)?;
diff --git a/afl/src/executors/inmemory.rs b/afl/src/executors/inmemory.rs
index 9f23506ec9..e2fd5ceb63 100644
--- a/afl/src/executors/inmemory.rs
+++ b/afl/src/executors/inmemory.rs
@@ -4,7 +4,6 @@ use core::ptr;
 use crate::executors::{Executor, ExitKind};
 use crate::inputs::Input;
 use crate::observers::observer_serde::NamedSerdeAnyMap;
-use crate::observers::Observer;
 use crate::AflError;
 
 type HarnessFunction<I> = fn(&dyn Executor<I>, &[u8]) -> ExitKind;
diff --git a/afl/src/mutators/mutations.rs b/afl/src/mutators/mutations.rs
index 032efc1f9f..64c3aa5bce 100644
--- a/afl/src/mutators/mutations.rs
+++ b/afl/src/mutators/mutations.rs
@@ -686,13 +686,13 @@ where
     R: Rand,
 {
     // We don't want to use the testcase we're already using for splicing
-    let (other_testcase, _) = corpus.random_entry(rand)?.clone();
-    // TODO: Load let other = Testcase::load_from_disk(other_test)?;
+    let (other_testcase, idx) = corpus.random_entry(rand)?;
+    if idx == corpus.current_testcase().1 {
+        return Ok(MutationResult::Skipped);
+    }
     // println!("Input: {:?}, other input: {:?}", input.bytes(), other.bytes());
-    let other = match other_testcase.input() {
-        Some(i) => i,
-        None => return Ok(MutationResult::Skipped), //TODO
-    };
+    let mut other_ref = other_testcase.borrow_mut();
+    let other = other_ref.load_input()?;
 
     let mut counter = 0;
     let (first_diff, last_diff) = loop {
diff --git a/afl/src/mutators/scheduled.rs b/afl/src/mutators/scheduled.rs
index eb342a8ad6..62ee7df245 100644
--- a/afl/src/mutators/scheduled.rs
+++ b/afl/src/mutators/scheduled.rs
@@ -265,7 +265,7 @@ mod tests {
         let (testcase, _) = corpus
             .next(&mut rand)
             .expect("Corpus did not contain entries");
-        let mut input = testcase.input().as_ref().unwrap().clone();
+        let mut input = testcase.borrow_mut().load_input().unwrap().clone();
 
         rand.set_seed(5);
         let mut mutator = StdScheduledMutator::new();
diff --git a/afl/src/stages/mod.rs b/afl/src/stages/mod.rs
index 49fd2d81fa..97881719ef 100644
--- a/afl/src/stages/mod.rs
+++ b/afl/src/stages/mod.rs
@@ -24,6 +24,6 @@ where
         state: &mut State<I, R>,
         corpus: &mut C,
         engine: &mut Engine<EM, E, C, I, R>,
-        input: &I,
+        corpus_idx: usize,
     ) -> Result<(), AflError>;
 }
diff --git a/afl/src/stages/mutational.rs b/afl/src/stages/mutational.rs
index 164dff94ce..9c455d6d4f 100644
--- a/afl/src/stages/mutational.rs
+++ b/afl/src/stages/mutational.rs
@@ -40,11 +40,11 @@ where
         state: &mut State<I, R>,
         corpus: &mut C,
         engine: &mut Engine<EM, E, C, I, R>,
-        input: &I,
+        corpus_idx: usize,
     ) -> Result<(), AflError> {
         let num = self.iterations(rand);
         for i in 0..num {
-            let mut input_mut = input.clone();
+            let mut input_mut = corpus.get(corpus_idx).borrow_mut().load_input()?.clone();
             self.mutator_mut()
                 .mutate(rand, corpus, &mut input_mut, i as i32)?;
 
@@ -120,9 +120,9 @@ where
         state: &mut State<I, R>,
         corpus: &mut C,
         engine: &mut Engine<EM, E, C, I, R>,
-        input: &I,
+        corpus_idx: usize,
     ) -> Result<(), AflError> {
-        self.perform_mutational(rand, state, corpus, engine, input)
+        self.perform_mutational(rand, state, corpus, engine, corpus_idx)
     }
 }