diff --git a/.gitignore b/.gitignore
index 800ae845..e8a5296c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,3 +12,5 @@ setup.*
 .ignore
 _opam
 *.exe
+fuzz-*-input
+fuzz-*-output
diff --git a/fuzz/ccsexp_parse_string_does_not_crash.ml b/fuzz/ccsexp_parse_string_does_not_crash.ml
new file mode 100644
index 00000000..358968c2
--- /dev/null
+++ b/fuzz/ccsexp_parse_string_does_not_crash.ml
@@ -0,0 +1,3 @@
+let () =
+  Crowbar.add_test ~name:"ccsexp_parse_string_does_not_crash" [ Crowbar.bytes ]
+    (fun s -> CCSexp.parse_string s |> ignore)
diff --git a/fuzz/ccutf8_string_uchar_to_bytes_is_same_as_simple_version.ml b/fuzz/ccutf8_string_uchar_to_bytes_is_same_as_simple_version.ml
new file mode 100644
index 00000000..af930e6c
--- /dev/null
+++ b/fuzz/ccutf8_string_uchar_to_bytes_is_same_as_simple_version.ml
@@ -0,0 +1,168 @@
+let simple_uchar_to_string (c : Uchar.t) : string =
+  let c = Uchar.to_int c in
+  let bits =
+    Array.make 64 false
+    |> Array.mapi (fun i _ ->
+        ((Int.shift_right c (63 - i)) land 0x1) <> 0
+      )
+  in
+  let char_of_bit_list bits =
+    let bits = Array.of_list bits in
+    assert (Array.length bits = 8);
+    let res = ref 0 in
+    for i=0 to 7 do
+      if bits.(i) then
+        res := !res lor (0x1 lsl (7-i))
+    done;
+    Char.chr !res
+  in
+  let get_start_from_right i =
+    Array.get bits (63 - i)
+  in
+  let chars =
+    if c <= 0x7F then (
+      [
+        [
+          false;
+          get_start_from_right 6;
+          get_start_from_right 5;
+          get_start_from_right 4;
+          get_start_from_right 3;
+          get_start_from_right 2;
+          get_start_from_right 1;
+          get_start_from_right 0;
+        ]
+      ]
+    )
+    else if c <= 0x7FF then (
+      [
+        [
+          true;
+          true;
+          false;
+          get_start_from_right 10;
+          get_start_from_right 9;
+          get_start_from_right 8;
+          get_start_from_right 7;
+          get_start_from_right 6;
+        ];
+        [
+          true;
+          false;
+          get_start_from_right 5;
+          get_start_from_right 4;
+          get_start_from_right 3;
+          get_start_from_right 2;
+          get_start_from_right 1;
+          get_start_from_right 0;
+        ];
+      ]
+    )
+    else if c <= 0xFFFF then (
+      [
+        [
+          true;
+          true;
+          true;
+          false;
+          get_start_from_right 15;
+          get_start_from_right 14;
+          get_start_from_right 13;
+          get_start_from_right 12;
+        ];
+        [
+          true;
+          false;
+          get_start_from_right 11;
+          get_start_from_right 10;
+          get_start_from_right 9;
+          get_start_from_right 8;
+          get_start_from_right 7;
+          get_start_from_right 6;
+        ];
+        [
+          true;
+          false;
+          get_start_from_right 5;
+          get_start_from_right 4;
+          get_start_from_right 3;
+          get_start_from_right 2;
+          get_start_from_right 1;
+          get_start_from_right 0;
+        ];
+      ]
+    )
+    else if c <= 0x10FFFF then (
+      [
+        [
+          true;
+          true;
+          true;
+          true;
+          false;
+          get_start_from_right 20;
+          get_start_from_right 19;
+          get_start_from_right 18;
+        ];
+        [
+          true;
+          false;
+          get_start_from_right 17;
+          get_start_from_right 16;
+          get_start_from_right 15;
+          get_start_from_right 14;
+          get_start_from_right 13;
+          get_start_from_right 12;
+        ];
+        [
+          true;
+          false;
+          get_start_from_right 11;
+          get_start_from_right 10;
+          get_start_from_right 9;
+          get_start_from_right 8;
+          get_start_from_right 7;
+          get_start_from_right 6;
+        ];
+        [
+          true;
+          false;
+          get_start_from_right 5;
+          get_start_from_right 4;
+          get_start_from_right 3;
+          get_start_from_right 2;
+          get_start_from_right 1;
+          get_start_from_right 0;
+        ];
+      ]
+    )
+    else (
+      failwith "Unexpected case"
+    )
+  in
+  chars
+  |> List.map char_of_bit_list
+  |> List.to_seq
+  |> String.of_seq
+
+let () =
+  Crowbar.add_test ~name:"ccutf8_string_uchar_to_bytes_is_same_as_simple_version" [ Crowbar.range (succ 0x10FFFF) ]
+    (fun c ->
+       Crowbar.guard (Uchar.is_valid c);
+       let c = Uchar.of_int c in
+       let simple_answer =
+         simple_uchar_to_string c
+       in
+       let answer =
+         let buf = ref [] in
+         CCUtf8_string.uchar_to_bytes c (fun c ->
+             buf := c :: !buf;
+           );
+         !buf
+         |> List.rev
+         |> List.to_seq
+         |> String.of_seq
+       in
+       Crowbar.check_eq
+         simple_answer answer
+    )
diff --git a/fuzz/dune b/fuzz/dune
new file mode 100644
index 00000000..cdc34acc
--- /dev/null
+++ b/fuzz/dune
@@ -0,0 +1,9 @@
+(executables
+ (flags     (-w "+a-4-9-29-37-40-42-44-48-50-32" -g))
+ (names     ccsexp_parse_string_does_not_crash
+            ccutf8_string_uchar_to_bytes_is_same_as_simple_version
+ )
+ (libraries crowbar
+            containers
+ )
+)
diff --git a/fuzz/list.sh b/fuzz/list.sh
new file mode 100755
index 00000000..eafc9162
--- /dev/null
+++ b/fuzz/list.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+script_dir=$(dirname $(readlink -f "$0"))
+
+echo "Building"
+
+dune build @all
+
+echo ""
+
+echo "Fuzzing tests available:"
+
+for file in "$script_dir"/../_build/default/fuzz/*.exe; do
+  echo "- "$(basename $file | sed 's/\.exe$//')
+done
diff --git a/fuzz/run.sh b/fuzz/run.sh
new file mode 100755
index 00000000..8bdd3b88
--- /dev/null
+++ b/fuzz/run.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+
+script_dir=$(dirname $(readlink -f "$0"))
+
+echo "Building"
+
+dune build @all
+
+if [[ "$1" == "" ]]; then
+  echo "Please enter a fuzzing test to run"
+  exit 1
+fi
+
+name=$(echo "$1" | sed 's/\.exe$//')
+
+echo "Creating input directory"
+
+input_dir="$script_dir"/../"fuzz-""$name""-input"
+
+output_dir="$script_dir"/../"fuzz-""$name""-output"
+
+mkdir -p "$input_dir"
+
+echo "abcd" > "$input_dir"/dummy
+
+mkdir -p "$output_dir"
+
+afl-fuzz -t 1000 -i "$input_dir" -o "$output_dir" "$script_dir"/../_build/default/fuzz/"$name".exe @@