diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index b84d048..868fb48 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/antonbabenko/pre-commit-terraform
-    rev: v1.99.4
+    rev: v1.100.0
     hooks:
       - id: terraform_fmt
       - id: terraform_wrapper_module_for_each
@@ -24,7 +24,7 @@ repos:
           - '--args=--only=terraform_workspace_remote'
       - id: terraform_validate
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v5.0.0
+    rev: v6.0.0
     hooks:
       - id: check-merge-conflict
       - id: end-of-file-fixer
diff --git a/README.md b/README.md
index 38c6c25..6bfbe6e 100644
--- a/README.md
+++ b/README.md
@@ -208,7 +208,7 @@ No modules.
 | <a name="input_ebs_options"></a> [ebs\_options](#input\_ebs\_options) | Configuration block for EBS related options, may be required based on chosen [instance size](https://aws.amazon.com/elasticsearch-service/pricing/) | `any` | <pre>{<br/>  "ebs_enabled": true,<br/>  "volume_size": 64,<br/>  "volume_type": "gp3"<br/>}</pre> | no |
 | <a name="input_enable_access_policy"></a> [enable\_access\_policy](#input\_enable\_access\_policy) | Determines whether an access policy will be applied to the domain | `bool` | `true` | no |
 | <a name="input_encrypt_at_rest"></a> [encrypt\_at\_rest](#input\_encrypt\_at\_rest) | Configuration block for encrypting at rest | `any` | <pre>{<br/>  "enabled": true<br/>}</pre> | no |
-| <a name="input_engine_version"></a> [engine\_version](#input\_engine\_version) | Version of the OpenSearch engine to use | `string` | `null` | no |
+| <a name="input_engine_version"></a> [engine\_version](#input\_engine\_version) | Version of the OpenSearch engine to use. Must follow format 'OpenSearch\_X.Y' (e.g., 'OpenSearch\_2.11') | `string` | `null` | no |
 | <a name="input_ip_address_type"></a> [ip\_address\_type](#input\_ip\_address\_type) | The IP address type for the endpoint. Valid values are ipv4 and dualstack | `string` | `null` | no |
 | <a name="input_log_publishing_options"></a> [log\_publishing\_options](#input\_log\_publishing\_options) | Configuration block for publishing slow and application logs to CloudWatch Logs. This block can be declared multiple times, for each log\_type, within the same resource | `any` | <pre>[<br/>  {<br/>    "log_type": "INDEX_SLOW_LOGS"<br/>  },<br/>  {<br/>    "log_type": "SEARCH_SLOW_LOGS"<br/>  }<br/>]</pre> | no |
 | <a name="input_node_to_node_encryption"></a> [node\_to\_node\_encryption](#input\_node\_to\_node\_encryption) | Configuration block for node-to-node encryption options | `any` | <pre>{<br/>  "enabled": true<br/>}</pre> | no |
diff --git a/variables.tf b/variables.tf
index 02bfafd..391eaed 100644
--- a/variables.tf
+++ b/variables.tf
@@ -86,9 +86,23 @@ variable "encrypt_at_rest" {
 }
 
 variable "engine_version" {
-  description = "Version of the OpenSearch engine to use"
+  description = "Version of the OpenSearch engine to use. Must follow format 'OpenSearch_X.Y' (e.g., 'OpenSearch_2.11')"
   type        = string
   default     = null
+
+  validation {
+    condition     = var.engine_version == null || can(regex("^(Elasticsearch_[0-9]{1}\\.[0-9]{1,2}|OpenSearch_[0-9]{1,2}\\.[0-9]{1,2})$", var.engine_version))
+    error_message = <<-EOT
+      The engine_version must be in the format:
+      - 'OpenSearch_X.Y' where X is 1-2 digits and Y is 1-2 digits (e.g., 'OpenSearch_2.11', 'OpenSearch_1.3')
+      - 'Elasticsearch_X.Y' where X is 1 digit and Y is 1-2 digits (e.g., 'Elasticsearch_7.10')
+
+      Your provided value appears to be a software service version (with release dates/patches).
+      Please use only the engine version format. Common valid versions include:
+      - OpenSearch_1.0, OpenSearch_1.1, OpenSearch_1.2, OpenSearch_1.3
+      - OpenSearch_2.0, OpenSearch_2.3, OpenSearch_2.5, OpenSearch_2.7, OpenSearch_2.9, OpenSearch_2.11
+    EOT
+  }
 }
 
 variable "ip_address_type" {