diff --git a/system/Database/Forge.php b/system/Database/Forge.php
index 8ad39ae5a574..c95ced88c4d6 100644
--- a/system/Database/Forge.php
+++ b/system/Database/Forge.php
@@ -387,12 +387,25 @@ public function addField($field)
                     throw new InvalidArgumentException('Field information is required for that operation.');
                 }
 
-                $this->fields[] = $field;
+                $fieldName = explode(' ', $field, 2)[0];
+                $fieldName = trim($fieldName, '`\'"');
+
+                $this->fields[$fieldName] = $field;
             }
         }
 
         if (is_array($field)) {
-            $this->fields = array_merge($this->fields, $field);
+            foreach ($field as $idx => $f) {
+                if (is_string($f)) {
+                    $this->addField($f);
+
+                    continue;
+                }
+
+                if (is_array($f)) {
+                    $this->fields = array_merge($this->fields, [$idx => $f]);
+                }
+            }
         }
 
         return $this;
@@ -878,7 +891,7 @@ protected function _processFields(bool $createTable = false): array
         $fields = [];
 
         foreach ($this->fields as $key => $attributes) {
-            if (is_int($key) && ! is_array($attributes)) {
+            if (! is_array($attributes)) {
                 $fields[] = ['_literal' => $attributes];
 
                 continue;
diff --git a/tests/system/Database/Live/ForgeTest.php b/tests/system/Database/Live/ForgeTest.php
index 63681115f2ad..1eba35919068 100644
--- a/tests/system/Database/Live/ForgeTest.php
+++ b/tests/system/Database/Live/ForgeTest.php
@@ -415,6 +415,43 @@ public function testForeignKey()
         $this->forge->dropTable('forge_test_users', true);
     }
 
+    /**
+     * @see https://github.com/codeigniter4/CodeIgniter4/issues/4986
+     */
+    public function testForeignKeyAddingWithStringFields()
+    {
+        if ($this->db->DBDriver !== 'MySQLi') {
+            $this->markTestSkipped('Testing only on MySQLi but fix expands to all DBs.');
+        }
+
+        $attributes = ['ENGINE' => 'InnoDB'];
+
+        $this->forge->addField([
+            '`id` INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY',
+            '`name` VARCHAR(255) NOT NULL',
+        ])->createTable('forge_test_users', true, $attributes);
+
+        $this->forge
+            ->addField([
+                '`id` INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY',
+                '`users_id` INT(11) NOT NULL',
+                '`name` VARCHAR(255) NOT NULL',
+            ])
+            ->addForeignKey('users_id', 'forge_test_users', 'id', 'CASCADE', 'CASCADE')
+            ->createTable('forge_test_invoices', true, $attributes);
+
+        $foreignKeyData = $this->db->getForeignKeyData('forge_test_invoices')[0];
+
+        $this->assertSame($this->db->DBPrefix . 'forge_test_invoices_users_id_foreign', $foreignKeyData->constraint_name);
+        $this->assertSame('users_id', $foreignKeyData->column_name);
+        $this->assertSame('id', $foreignKeyData->foreign_column_name);
+        $this->assertSame($this->db->DBPrefix . 'forge_test_invoices', $foreignKeyData->table_name);
+        $this->assertSame($this->db->DBPrefix . 'forge_test_users', $foreignKeyData->foreign_table_name);
+
+        $this->forge->dropTable('forge_test_invoices', true);
+        $this->forge->dropTable('forge_test_users', true);
+    }
+
     public function testForeignKeyFieldNotExistException()
     {
         $this->expectException(DatabaseException::class);