diff --git a/mithril-client/src/aggregator.rs b/mithril-client/src/aggregator.rs
index 2095794ad2a..0fabb008841 100644
--- a/mithril-client/src/aggregator.rs
+++ b/mithril-client/src/aggregator.rs
@@ -106,7 +106,7 @@ impl AggregatorHTTPClient {
 
     /// Forge a client request adding protocol version in the headers.
     pub fn prepare_request_builder(&self, request_builder: RequestBuilder) -> RequestBuilder {
-        request_builder.header("API_VERSION", MITHRIL_API_VERSION)
+        request_builder.header("mithril-api-version", MITHRIL_API_VERSION)
     }
 
     /// Download certificate details
diff --git a/mithril-signer/src/certificate_handler.rs b/mithril-signer/src/certificate_handler.rs
index ae5c360350d..6afe0ceeead 100644
--- a/mithril-signer/src/certificate_handler.rs
+++ b/mithril-signer/src/certificate_handler.rs
@@ -94,7 +94,7 @@ impl CertificateHandlerHTTPClient {
 
     /// Forge a client request adding protocol version in the headers.
     pub fn prepare_request_builder(&self, request_builder: RequestBuilder) -> RequestBuilder {
-        request_builder.header("API_VERSION", MITHRIL_API_VERSION)
+        request_builder.header("mithril-api-version", MITHRIL_API_VERSION)
     }
 
     /// API version error handling