diff --git a/crates/llm_gateway/src/stream_context.rs b/crates/llm_gateway/src/stream_context.rs
index 0b932832..d08602ec 100644
--- a/crates/llm_gateway/src/stream_context.rs
+++ b/crates/llm_gateway/src/stream_context.rs
@@ -145,7 +145,7 @@ impl StreamContext {
             Some(SupportedAPIs::AnthropicMessagesAPI(_)) => {
                 // Anthropic API requires x-api-key and anthropic-version headers
                 // Remove any existing Authorization header since Anthropic doesn't use it
-                self.set_http_request_header("authorization", None);
+                self.set_http_request_header("Authorization", None);
                 self.set_http_request_header("x-api-key", Some(llm_provider_api_key_value));
                 self.set_http_request_header("anthropic-version", Some("2023-06-01"));
             }
@@ -154,7 +154,7 @@ impl StreamContext {
                 // Remove any existing x-api-key header since OpenAI doesn't use it
                 self.set_http_request_header("x-api-key", None);
                 let authorization_header_value = format!("Bearer {}", llm_provider_api_key_value);
-                self.set_http_request_header("authorization", Some(&authorization_header_value));
+                self.set_http_request_header("Authorization", Some(&authorization_header_value));
             }
         }
 
diff --git a/crates/llm_gateway/tests/integration.rs b/crates/llm_gateway/tests/integration.rs
index 24301111..eba90ad5 100644
--- a/crates/llm_gateway/tests/integration.rs
+++ b/crates/llm_gateway/tests/integration.rs
@@ -39,7 +39,8 @@ fn request_headers_expectations(module: &mut Tester, http_context: i32) {
             Some("x-arch-llm-provider"),
             Some("openai"),
         )
-        .expect_replace_header_map_value(
+        .expect_remove_header_map_value(Some(MapType::HttpRequestHeaders), Some("x-api-key"))
+        .expect_add_header_map_value(
             Some(MapType::HttpRequestHeaders),
             Some("Authorization"),
             Some("Bearer secret_key"),