diff --git a/src/connection/http2.rs b/src/connection/http2.rs
index dad1bcc..c46c049 100644
--- a/src/connection/http2.rs
+++ b/src/connection/http2.rs
@@ -660,7 +660,7 @@ pub async fn do_connection_loop(
                 // RFC 9113 6.1: `If a DATA frame is received whose Stream
                 // Identifier field is 0x00, the recipient MUST respond with a
                 // connection error`
-                if frame.stream_identifier == 0 {
+                if frame.stream_identifier == 0 && frame.length > 0 {
                     return Err(ConnectionError::DataOnStreamZero);
                 }
 
diff --git a/src/http2/frames/frame.rs b/src/http2/frames/frame.rs
index 878c24f..e8dba1d 100644
--- a/src/http2/frames/frame.rs
+++ b/src/http2/frames/frame.rs
@@ -18,6 +18,8 @@ pub enum FrameError {
     WindowUpdateTooBig,
     #[error("Frame is too big ({actual} > {max_frame_size})")]
     FrameTooBig { actual: u32, max_frame_size: u32 },
+    #[error("Header frame contains uppercase header")]
+    UppercaseHeader,
     // #[error("Continuation frame without header frame")]
     // ContinuationWithoutHeader,
     // #[error("Continuation frame but END_HEADERS set")]
diff --git a/src/http2/frames/headers.rs b/src/http2/frames/headers.rs
index 8457964..130fd3b 100644
--- a/src/http2/frames/headers.rs
+++ b/src/http2/frames/headers.rs
@@ -66,7 +66,16 @@ impl Headers {
                 headers: hds
                     .into_iter()
                     .map(|(k, v)| (Bytes::from(k), Bytes::from(v)))
-                    .collect(),
+                    .map(|(k, v)| {
+                        if k.iter()
+                            .all(|c| c.is_ascii_uppercase() || c.is_ascii_punctuation())
+                        {
+                            Err(FrameError::UppercaseHeader)
+                        } else {
+                            Ok((k, v))
+                        }
+                    })
+                    .collect::<Result<Vec<(Bytes, Bytes)>, FrameError>>()?,
                 end_stream: Self::is_end_stream(flags),
             }),
             Err(err) => {