diff --git a/src/morethantext/cache.rs b/src/morethantext/cache.rs
index ddc25db..af75c3c 100644
--- a/src/morethantext/cache.rs
+++ b/src/morethantext/cache.rs
@@ -1,10 +1,12 @@
 use super::{DBError, FileData, SessionData, Store};
-use async_std::{fs::{read, write}, path::Path};
+use async_std::{
+    fs::{read, remove_file, write},
+    path::Path,
+};
 use rand::{distributions::Alphanumeric, thread_rng, Rng};
 use std::{
     cell::Cell,
-    slice,
-    str,
+    slice, str,
     time::{Duration, Instant},
 };
 
@@ -50,7 +52,7 @@ impl FileData<Self> for DataType {
                 output.append(&mut "DBMap".as_bytes().to_vec());
                 output.push(0);
                 output.append(&mut store.to_bytes());
-            },
+            }
         }
         output
     }
@@ -73,11 +75,9 @@ impl FileData<Self> for DataType {
             Err(_) => return Err(DBError::new("file corruption")),
         };
         match header {
-            "DBMap" => {
-                match Store::from_bytes(data) {
-                    Ok(store) => Ok(DataType::DBMap(store)),
-                    Err(err) => Err(err),
-                }
+            "DBMap" => match Store::from_bytes(data) {
+                Ok(store) => Ok(DataType::DBMap(store)),
+                Err(err) => Err(err),
             },
             _ => Err(DBError::new("file corruption")),
         }
@@ -120,6 +120,21 @@ impl Entry {
         self.last_used.set(Instant::now());
         Ok(self.data.clone())
     }
+
+    async fn update(&mut self, data: DataType) -> Result<(), DBError> {
+        self.last_used.set(Instant::now());
+        let filepath = Path::new(&self.filename);
+        match write(filepath, data.to_bytes()).await {
+            Ok(_) => (),
+            Err(err) => {
+                let mut error = DBError::new("write error");
+                error.add_source(err);
+                return Err(error);
+            }
+        };
+        self.data = data;
+        Ok(())
+    }
 }
 
 struct Cache;
@@ -194,7 +209,10 @@ mod datatype_file {
         let data = dt_store.to_bytes();
         let mut feed = data.iter();
         let output = DataType::from_bytes(&mut feed).unwrap();
-        assert_eq!(dt_store.list(["database"].to_vec()).unwrap(), output.list(["database"].to_vec()).unwrap());
+        assert_eq!(
+            dt_store.list(["database"].to_vec()).unwrap(),
+            output.list(["database"].to_vec()).unwrap()
+        );
     }
 
     #[test]
@@ -204,7 +222,10 @@ mod datatype_file {
         let data = dt_store.to_bytes();
         let mut feed = data.iter();
         let output = DataType::from_bytes(&mut feed).unwrap();
-        assert_eq!(dt_store.list(["database"].to_vec()).unwrap(), output.list(["database"].to_vec()).unwrap());
+        assert_eq!(
+            dt_store.list(["database"].to_vec()).unwrap(),
+            output.list(["database"].to_vec()).unwrap()
+        );
     }
 
     #[test]
@@ -216,7 +237,7 @@ mod datatype_file {
             Err(err) => {
                 assert_eq!(err.to_string(), "file corruption");
                 Ok(())
-            },
+            }
         }
     }
 
@@ -231,7 +252,7 @@ mod datatype_file {
             Err(err) => {
                 assert_eq!(err.to_string(), "file corruption");
                 Ok(())
-            },
+            }
         }
     }
 }
@@ -249,9 +270,16 @@ mod entry {
         let filepath = dir.path().join("count");
         let filename = filepath.to_str().unwrap();
         let item = Entry::new(filename.to_string(), data).await.unwrap();
-        assert!(Duration::from_secs(1) > item.elapsed(), "last_used should have been now.");
-        item.last_used.set(Instant::now() - Duration::from_secs(500));
-        assert!(Duration::from_secs(499) < item.elapsed(), "The duration should have increased.");
+        assert!(
+            Duration::from_secs(1) > item.elapsed(),
+            "last_used should have been now."
+        );
+        item.last_used
+            .set(Instant::now() - Duration::from_secs(500));
+        assert!(
+            Duration::from_secs(499) < item.elapsed(),
+            "The duration should have increased."
+        );
     }
 
     #[async_std::test]
@@ -264,7 +292,10 @@ mod entry {
         let item = Entry::new(filename.to_string(), data.clone())
             .await
             .unwrap();
-        assert!(Duration::from_secs(1) > item.elapsed(), "last_used should have been now.");
+        assert!(
+            Duration::from_secs(1) > item.elapsed(),
+            "last_used should have been now."
+        );
         let output = item.get().await.unwrap();
         assert_eq!(
             data.list(["database"].to_vec()).unwrap(),
@@ -286,7 +317,11 @@ mod entry {
             Err(err) => {
                 assert_eq!(err.to_string(), "failed to write");
                 assert!(err.source().is_some(), "Must include the source error.");
-                assert!(err.source().unwrap().to_string().contains("could not write to file"));
+                assert!(err
+                    .source()
+                    .unwrap()
+                    .to_string()
+                    .contains("could not write to file"));
                 Ok(())
             }
         }
@@ -320,9 +355,64 @@ mod entry {
         let filepath = dir.path().join("holder");
         let filename = filepath.to_str().unwrap();
         let item = Entry::new(filename.to_string(), data).await.unwrap();
-        item.last_used.set(Instant::now() - Duration::from_secs(300));
+        item.last_used
+            .set(Instant::now() - Duration::from_secs(300));
         item.get().await.unwrap();
-        assert!(Duration::from_secs(1) > item.elapsed(), "last_used should have been reset.");
+        assert!(
+            Duration::from_secs(1) > item.elapsed(),
+            "last_used should have been reset."
+        );
+    }
+
+    #[async_std::test]
+    async fn update_entry() {
+        let dir = tempdir().unwrap();
+        let mut data = DataType::new("store").unwrap();
+        let filepath = dir.path().join("changing");
+        let filename = filepath.to_str().unwrap();
+        let mut item = Entry::new(filename.to_string(), data.clone())
+            .await
+            .unwrap();
+        item.last_used
+            .set(Instant::now() - Duration::from_secs(500));
+        data.add("database", "new", "stuff").unwrap();
+        item.update(data.clone()).await.unwrap();
+        assert!(
+            Duration::from_secs(1) > item.elapsed(),
+            "last_used should have been reset."
+        );
+        let output = item.get().await.unwrap();
+        assert_eq!(
+            data.list(["database"].to_vec()).unwrap(),
+            output.list(["database"].to_vec()).unwrap()
+        );
+        let content = read(&filepath).await.unwrap();
+        assert_eq!(content, data.to_bytes());
+    }
+
+    #[async_std::test]
+    async fn update_write_errors() -> Result<(), DBError> {
+        let dir = tempdir().unwrap();
+        let data = DataType::new("store").unwrap();
+        let filepath = dir.path().join("changing");
+        let filename = filepath.to_str().unwrap();
+        let mut item = Entry::new(filename.to_string(), data.clone())
+            .await
+            .unwrap();
+        drop(dir);
+        match item.update(data).await {
+            Ok(_) => Err(DBError::new("file writes should return an error")),
+            Err(err) => {
+                assert_eq!(err.to_string(), "write error");
+                assert!(err.source().is_some(), "Must include the source error.");
+                assert!(err
+                    .source()
+                    .unwrap()
+                    .to_string()
+                    .contains("could not write to file"));
+                Ok(())
+            }
+        }
     }
 }