diff --git a/langfuse/_client/span_processor.py b/langfuse/_client/span_processor.py
index baa72360c..369d5ff9e 100644
--- a/langfuse/_client/span_processor.py
+++ b/langfuse/_client/span_processor.py
@@ -83,9 +83,9 @@ def __init__(
         # Prepare default headers
         default_headers = {
             "Authorization": basic_auth_header,
-            "x_langfuse_sdk_name": "python",
-            "x_langfuse_sdk_version": langfuse_version,
-            "x_langfuse_public_key": public_key,
+            "x-langfuse-sdk-name": "python",
+            "x-langfuse-sdk-version": langfuse_version,
+            "x-langfuse-public-key": public_key,
         }
 
         # Merge additional headers if provided
diff --git a/langfuse/_utils/request.py b/langfuse/_utils/request.py
index b106cee2f..182fe3ffe 100644
--- a/langfuse/_utils/request.py
+++ b/langfuse/_utils/request.py
@@ -41,9 +41,9 @@ def generate_headers(self) -> dict:
                 f"{self._public_key}:{self._secret_key}".encode("utf-8")
             ).decode("ascii"),
             "Content-Type": "application/json",
-            "x_langfuse_sdk_name": "python",
-            "x_langfuse_sdk_version": self._version,
-            "x_langfuse_public_key": self._public_key,
+            "x-langfuse-sdk-name": "python",
+            "x-langfuse-sdk-version": self._version,
+            "x-langfuse-public-key": self._public_key,
         }
 
     def batch_post(self, **kwargs: Any) -> httpx.Response:
diff --git a/tests/test_additional_headers_simple.py b/tests/test_additional_headers_simple.py
index 4298a3ba5..8a1d07134 100644
--- a/tests/test_additional_headers_simple.py
+++ b/tests/test_additional_headers_simple.py
@@ -156,8 +156,8 @@ def test_span_processor_has_additional_headers_in_otel_exporter(self):
 
         # Verify default headers are still present
         assert "Authorization" in exporter._headers
-        assert "x_langfuse_sdk_name" in exporter._headers
-        assert "x_langfuse_public_key" in exporter._headers
+        assert "x-langfuse-sdk-name" in exporter._headers
+        assert "x-langfuse-public-key" in exporter._headers
 
         # Check that our override worked
         assert exporter._headers["X-Override-Default"] == "override-value"
@@ -179,5 +179,5 @@ def test_span_processor_none_additional_headers_works(self):
 
         # Verify default headers are present
         assert "Authorization" in exporter._headers
-        assert "x_langfuse_sdk_name" in exporter._headers
-        assert "x_langfuse_public_key" in exporter._headers
+        assert "x-langfuse-sdk-name" in exporter._headers
+        assert "x-langfuse-public-key" in exporter._headers