diff --git a/src/database/table.rs b/src/database/table.rs
index b42fd01..2a5786d 100644
--- a/src/database/table.rs
+++ b/src/database/table.rs
@@ -1,7 +1,10 @@
 use super::{index::Index, row::Row};
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
-use std::collections::{hash_map::Entry, HashMap};
+use std::{
+    borrow::Borrow,
+    collections::{hash_map::Entry, HashMap},
+};
 
 #[derive(Serialize, Deserialize)]
 pub struct Table {
@@ -41,6 +44,10 @@ impl Table {
             return Err("Primary key is not of type u64".to_string());
         }
 
+        if self.rows.contains_key(row_primary_key.unwrap().borrow()) {
+            return Err("Primary key already exists".to_string());
+        }
+
         // Insert row into database
         self.rows.insert(row_primary_key.unwrap(), row.clone());
 
diff --git a/src/tests/table_test.rs b/src/tests/table_test.rs
index f05a0be..8869961 100644
--- a/src/tests/table_test.rs
+++ b/src/tests/table_test.rs
@@ -29,4 +29,18 @@ mod table_test {
         let row = table.find_by_pk(3u64);
         assert_eq!(row.is_err(), true);
     }
+
+    #[test]
+    fn should_fail_to_insert_row_with_same_id() {
+        let mut table: Table = Table::new("Cats", "id", None);
+        let _ = table.insert_row(row!["id" => 1, "name" => "Ozzy"]);
+
+        // Make sure the rows actually exists
+        let row = table.find_by_pk(1u64);
+        assert_eq!(row.unwrap().get("id").unwrap(), 1u64);
+
+        let result = table.insert_row(row!["id" => 1, "name" => "Simon"]);
+
+        assert_eq!(result.is_err(), true);
+    }
 }