diff --git a/include/haproxy/quic_frame.h b/include/haproxy/quic_frame.h
index ea33425..f75d7e6 100644
--- a/include/haproxy/quic_frame.h
+++ b/include/haproxy/quic_frame.h
@@ -254,5 +254,18 @@
 	*frm = NULL;
 }
 
+/* Move forward <strm> STREAM frame by <data> bytes. */
+static inline void qc_stream_frm_mv_fwd(struct quic_stream *strm, uint64_t data)
+{
+	struct buffer cf_buf;
+
+	strm->offset.key += data;
+	strm->len -= data;
+	cf_buf = b_make(b_orig(strm->buf),
+	                b_size(strm->buf),
+	                (char *)strm->data - b_orig(strm->buf), 0);
+	strm->data = (unsigned char *)b_peek(&cf_buf, data);
+}
+
 #endif /* USE_QUIC */
 #endif /* _HAPROXY_QUIC_FRAME_H */
diff --git a/src/quic_conn.c b/src/quic_conn.c
index 6fd8412..5fa2ce9 100644
--- a/src/quic_conn.c
+++ b/src/quic_conn.c
@@ -1897,8 +1897,9 @@
 				continue;
 			}
 			else if (strm_frm->offset.key < stream_desc->ack_offset) {
-				strm_frm->offset.key = stream_desc->ack_offset;
-				strm_frm->len -= stream_desc->ack_offset - strm_frm->offset.key;
+				uint64_t diff = stream_desc->ack_offset - strm_frm->offset.key;
+
+				qc_stream_frm_mv_fwd(strm_frm, diff);
 				TRACE_DEVEL("updated partially acked frame",
 				            QUIC_EV_CONN_PRSAFRM, qc, frm);
 			}
@@ -2553,8 +2554,9 @@
 				continue;
 			}
 			else if (strm_frm->offset.key < stream_desc->ack_offset) {
-				strm_frm->offset.key = stream_desc->ack_offset;
-				strm_frm->len -= stream_desc->ack_offset - strm_frm->offset.key;
+				uint64_t diff = stream_desc->ack_offset - strm_frm->offset.key;
+
+				qc_stream_frm_mv_fwd(strm_frm, diff);
 				TRACE_DEVEL("updated partially acked frame",
 				            QUIC_EV_CONN_PRSAFRM, qc, frm);
 			}
@@ -7289,8 +7291,9 @@
 					continue;
 				}
 				else if (strm->offset.key < stream_desc->ack_offset) {
-					strm->offset.key = stream_desc->ack_offset;
-					strm->len -= stream_desc->ack_offset - strm->offset.key;
+					uint64_t diff = stream_desc->ack_offset - strm->offset.key;
+
+					qc_stream_frm_mv_fwd(strm, diff);
 					TRACE_DEVEL("updated partially acked frame",
 					            QUIC_EV_CONN_PRSAFRM, qc, cf);
 				}