diff --git a/docs/migrating.md b/docs/migrating.md
index bff88fe..657f037 100644
--- a/docs/migrating.md
+++ b/docs/migrating.md
@@ -186,7 +186,7 @@ Use a `.elasticsearch:Elasticsearch` Sink.
 - `timeout`: moved to `client.timeout`.
 - `cert_path`: moved to `client.cert_path`.
 - `index_suffix`: no changes.
-- `index_prefix`: not supported - [GitHub Issue #12](https://github.com/nhairs/parsedmarc-fork/issues/12).
+- `index_prefix`: no changes.
 - `monthly_indexes`: no changes.
 - `number_of_shards`: no changes.
 - `number_of_replicas`: no changes.
diff --git a/src/parsedmarc/elastic.py b/src/parsedmarc/elastic.py
index 542f4fd..7baf6b4 100644
--- a/src/parsedmarc/elastic.py
+++ b/src/parsedmarc/elastic.py
@@ -194,6 +194,7 @@ def __init__(  # pylint: disable=too-many-positional-arguments
         api_key: str | None = None,
         timeout: float = 60.0,
         index_suffix: str | None = None,
+        index_prefix: str = "",
         monthly_indexes: bool = True,
         number_of_shards: int = 1,
         number_of_replicas: int = 0,
@@ -230,8 +231,8 @@ def __init__(  # pylint: disable=too-many-positional-arguments
         self.client = Elasticsearch(**conn_params)  # type: ignore[arg-type]
 
         ## Other settings
-        self.aggregate_index_base = "dmarc_aggregate"
-        self.forensic_index_base = "dmarc_forensic"
+        self.aggregate_index_base = f"{index_prefix}dmarc_aggregate"
+        self.forensic_index_base = f"{index_prefix}dmarc_forensic"
 
         if index_suffix:
             self.aggregate_index_base += f"_{index_suffix}"
diff --git a/src/parsedmarc/sink/elasticsearch.py b/src/parsedmarc/sink/elasticsearch.py
index 77f8d4a..5bfb8ab 100644
--- a/src/parsedmarc/sink/elasticsearch.py
+++ b/src/parsedmarc/sink/elasticsearch.py
@@ -41,6 +41,7 @@ def setup(self) -> None:
                 api_key=self.config.client.api_key,
                 timeout=self.config.client.timeout,
                 index_suffix=self.config.index_suffix,
+                index_prefix=self.config.index_prefix,
                 monthly_indexes=self.config.monthly_indexes,
                 number_of_shards=self.config.number_of_shards,
                 number_of_replicas=self.config.number_of_replicas,
@@ -85,6 +86,7 @@ class ElasticsearchConfig(BaseConfig):
 
     client: ElasticsearchClientConfig
     index_suffix: Union[str, None] = None
+    index_prefix: str = ""
     monthly_indexes: bool = True
     number_of_shards: int = 1
     number_of_replicas: int = 0