diff --git a/src/lib.rs b/src/lib.rs
index a8734cd..3bd7984 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -30,5 +30,7 @@ impl std::fmt::Display for Error {
     }
 }
 
+impl std::error::Error for Error {}
+
 /// Custom `Result` type with custom `Error` type
-pub type Result<T> = std::result::Result<T, Error>;
+pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
diff --git a/src/tree.rs b/src/tree.rs
index 3270442..ed7eb81 100644
--- a/src/tree.rs
+++ b/src/tree.rs
@@ -118,7 +118,7 @@ where
     /// Sets a leaf at the specified tree index
     pub fn set(&mut self, key: usize, leaf: H::Fr) -> Result<()> {
         if key >= self.capacity() {
-            return Err(Error("Merkle Tree is full!".to_string()));
+            return Err(Box::new(Error("Merkle Tree is full!".to_string())));
         }
 
         self.db
@@ -177,7 +177,7 @@ where
     /// Deletes a leaf at the `key` by setting it to its default value
     pub fn delete(&mut self, key: usize) -> Result<()> {
         if key >= self.next_index {
-            return Err(Error("The key doesn't exist!".to_string()));
+            return Err(Box::new(Error("The key doesn't exist!".to_string())));
         }
 
         self.set(key, H::default_leaf())?;
@@ -197,7 +197,9 @@ where
         let end = self.next_index + leaves.len();
 
         if end > self.capacity() {
-            return Err(Error("Not enough space to insert the leaves!".to_string()));
+            return Err(Box::new(Error(
+                "Not enough space to insert the leaves!".to_string(),
+            )));
         }
 
         let mut subtree = HashMap::<Key, H::Fr>::new();
@@ -309,7 +311,7 @@ where
     /// Computes a Merkle proof for the leaf at the specified index
     pub fn proof(&self, index: usize) -> Result<MerkleProof<H>> {
         if index >= self.capacity() {
-            return Err(Error("Index exceeds set size!".to_string()));
+            return Err(Box::new(Error("Index exceeds set size!".to_string())));
         }
 
         let mut witness = Vec::with_capacity(self.depth);
diff --git a/tests/memory_keccak.rs b/tests/memory_keccak.rs
index 921b71b..e389d3f 100644
--- a/tests/memory_keccak.rs
+++ b/tests/memory_keccak.rs
@@ -12,7 +12,7 @@ impl Database for MemoryDB {
     }
 
     fn load(_dbpath: &str) -> Result<Self> {
-        Err(Error("Cannot load in-memory DB".to_string()))
+        Err(Box::new(Error("Cannot load in-memory DB".to_string())))
     }
 
     fn get(&self, key: DBKey) -> Result<Option<Value>> {
diff --git a/tests/poseidon.rs b/tests/poseidon.rs
index 8426067..2f6117c 100644
--- a/tests/poseidon.rs
+++ b/tests/poseidon.rs
@@ -49,7 +49,7 @@ impl Database for MemoryDB {
     }
 
     fn load(_dbpath: &str) -> Result<Self> {
-        Err(Error("Cannot load in-memory DB".to_string()))
+        Err(Box::new(Error("Cannot load in-memory DB".to_string())))
     }
 
     fn get(&self, key: DBKey) -> Result<Option<Value>> {
@@ -73,7 +73,7 @@ impl Database for MySled {
     fn new(dbpath: &str) -> Result<Self> {
         let db = sled::open(dbpath).unwrap();
         if db.was_recovered() {
-            return Err(Error("Database exists, try load()!".to_string()));
+            return Err(Box::new(Error("Database exists, try load()!".to_string())));
         }
 
         Ok(MySled(db))
@@ -84,7 +84,9 @@ impl Database for MySled {
 
         if !db.was_recovered() {
             fs::remove_dir_all(dbpath).expect("Error removing db");
-            return Err(Error("Trying to load non-existing database!".to_string()));
+            return Err(Box::new(Error(
+                "Trying to load non-existing database!".to_string(),
+            )));
         }
 
         Ok(MySled(db))
diff --git a/tests/sled_keccak.rs b/tests/sled_keccak.rs
index 9eae448..2b05043 100644
--- a/tests/sled_keccak.rs
+++ b/tests/sled_keccak.rs
@@ -11,7 +11,7 @@ impl Database for MySled {
     fn new(dbpath: &str) -> Result<Self> {
         let db = sled::open(dbpath).unwrap();
         if db.was_recovered() {
-            return Err(Error("Database exists, try load()!".to_string()));
+            return Err(Box::new(Error("Database exists, try load()!".to_string())));
         }
 
         Ok(MySled(db))
@@ -22,7 +22,9 @@ impl Database for MySled {
 
         if !db.was_recovered() {
             fs::remove_dir_all(dbpath).expect("Error removing db");
-            return Err(Error("Trying to load non-existing database!".to_string()));
+            return Err(Box::new(Error(
+                "Trying to load non-existing database!".to_string(),
+            )));
         }
 
         Ok(MySled(db))