diff --git a/trunk/src/app/srs_app_rtc_source.cpp b/trunk/src/app/srs_app_rtc_source.cpp
index 4d1d6390a..ebfd088cb 100644
--- a/trunk/src/app/srs_app_rtc_source.cpp
+++ b/trunk/src/app/srs_app_rtc_source.cpp
@@ -1256,7 +1256,7 @@ srs_error_t SrsRtcRtpBuilder::package_nalus(SrsSharedPtrMessage* msg, const vect
         }
 
         if (first_nalu_type == SrsAvcNaluTypeReserved) {
-            first_nalu_type = SrsAvcNaluType((uint8_t)(sample->bytes[0] & kNalTypeMask));
+            first_nalu_type = SrsAvcNaluTypeParse(sample->bytes[0]);
         }
 
         raw_raw->push_back(sample->copy());
@@ -1336,7 +1336,7 @@ srs_error_t SrsRtcRtpBuilder::package_nalus(SrsSharedPtrMessage* msg, const vect
                     srs_freep(fua);
                     return srs_error_wrap(err, "read samples %d bytes, left %d, total %d", packet_size, nb_left, nn_bytes);
                 }
-                fua->nalu_type = (SrsAvcNaluType)(header & kNalTypeMask);
+                fua->nalu_type = SrsAvcNaluTypeParse(header);
                 fua->start = bool(i == 0);
                 fua->end = bool(i == num_of_packet - 1);
 
@@ -1409,25 +1409,23 @@ srs_error_t SrsRtcRtpBuilder::package_fu_a(SrsSharedPtrMessage* msg, SrsSample*
         pkt->nalu_type = is_hevc ? kFuHevc : kFuA;
 
         if (is_hevc) {
-            uint8_t nal_type = SrsHevcNaluTypeParse(header);
             // H265 FU-A header
             SrsRtpFUAPayloadHevc2* fua = new SrsRtpFUAPayloadHevc2();
             pkt->set_payload(fua, SrsRtspPacketPayloadTypeFUAHevc);
 
-            fua->nalu_type = (SrsHevcNaluType)nal_type;
+            fua->nalu_type = SrsHevcNaluTypeParse(header);
             fua->start = bool(i == 0);
             fua->end = bool(i == num_of_packet - 1);
 
             fua->payload = p;
             fua->size = packet_size;
         } else {
-            uint8_t nal_type = header & kNalTypeMask;
             // H264 FU-A header
             SrsRtpFUAPayload2* fua = new SrsRtpFUAPayload2();
             pkt->set_payload(fua, SrsRtspPacketPayloadTypeFUA2);
 
             fua->nri = (SrsAvcNaluType)header;
-            fua->nalu_type = (SrsAvcNaluType)nal_type;
+            fua->nalu_type = SrsAvcNaluTypeParse(header);
             fua->start = bool(i == 0);
             fua->end = bool(i == num_of_packet - 1);
 
diff --git a/trunk/src/kernel/srs_kernel_codec.cpp b/trunk/src/kernel/srs_kernel_codec.cpp
index 4dfc55bf7..38e68211a 100644
--- a/trunk/src/kernel/srs_kernel_codec.cpp
+++ b/trunk/src/kernel/srs_kernel_codec.cpp
@@ -707,7 +707,7 @@ srs_error_t SrsVideoFrame::parse_avc_nalu_type(const SrsSample* sample, SrsAvcNa
     }
     
     uint8_t header = sample->bytes[0];
-    avc_nalu_type = (SrsAvcNaluType)(header & kNalTypeMask);
+    avc_nalu_type = SrsAvcNaluTypeParse(header);
     
     return err;
 }
@@ -760,7 +760,7 @@ srs_error_t SrsVideoFrame::parse_hevc_nalu_type(const SrsSample *sample, SrsHevc
     }
     
     uint8_t header = sample->bytes[0];
-    hevc_nalu_type = (SrsHevcNaluType)((header >> 1) & 0x3f);
+    hevc_nalu_type = SrsHevcNaluTypeParse(header);
     
     return err;
 }
diff --git a/trunk/src/kernel/srs_kernel_codec.hpp b/trunk/src/kernel/srs_kernel_codec.hpp
index 8a1758667..e461b0790 100644
--- a/trunk/src/kernel/srs_kernel_codec.hpp
+++ b/trunk/src/kernel/srs_kernel_codec.hpp
@@ -422,6 +422,8 @@ enum SrsAvcNaluType
     // Coded slice extension slice_layer_extension_rbsp( )
     SrsAvcNaluTypeCodedSliceExt = 20,
 };
+// @see https://datatracker.ietf.org/doc/html/rfc6184#section-1.3
+#define SrsAvcNaluTypeParse(code) (SrsAvcNaluType)(code & 0x1F)
 std::string srs_avc_nalu2str(SrsAvcNaluType nalu_type);
 
 #ifdef SRS_H265
diff --git a/trunk/src/kernel/srs_kernel_rtc_rtp.cpp b/trunk/src/kernel/srs_kernel_rtc_rtp.cpp
index b547f233e..5ba2204ab 100644
--- a/trunk/src/kernel/srs_kernel_rtc_rtp.cpp
+++ b/trunk/src/kernel/srs_kernel_rtc_rtp.cpp
@@ -1208,7 +1208,7 @@ SrsSample* SrsRtpSTAPPayload::get_sps()
             continue;
         }
 
-        SrsAvcNaluType nalu_type = (SrsAvcNaluType)(p->bytes[0] & kNalTypeMask);
+        SrsAvcNaluType nalu_type = SrsAvcNaluTypeParse(p->bytes[0]);
         if (nalu_type == SrsAvcNaluTypeSPS) {
             return p;
         }
@@ -1226,7 +1226,7 @@ SrsSample* SrsRtpSTAPPayload::get_pps()
             continue;
         }
 
-        SrsAvcNaluType nalu_type = (SrsAvcNaluType)(p->bytes[0] & kNalTypeMask);
+        SrsAvcNaluType nalu_type = SrsAvcNaluTypeParse(p->bytes[0]);
         if (nalu_type == SrsAvcNaluTypePPS) {
             return p;
         }
@@ -1412,7 +1412,7 @@ srs_error_t SrsRtpFUAPayload::decode(SrsBuffer* buf)
     v = buf->read_1bytes();
     start = v & kStart;
     end = v & kEnd;
-    nalu_type = SrsAvcNaluType(v & kNalTypeMask);
+    nalu_type = SrsAvcNaluTypeParse(v);
 
     if (!buf->require(1)) {
         return srs_error_new(ERROR_RTC_RTP_MUXER, "requires %d bytes", 1);
@@ -1513,7 +1513,7 @@ srs_error_t SrsRtpFUAPayload2::decode(SrsBuffer* buf)
     v = buf->read_1bytes();
     start = v & kStart;
     end = v & kEnd;
-    nalu_type = SrsAvcNaluType(v & kNalTypeMask);
+    nalu_type = SrsAvcNaluTypeParse(v);
 
     if (!buf->require(1)) {
         return srs_error_new(ERROR_RTC_RTP_MUXER, "requires %d bytes", 1);
diff --git a/trunk/src/utest/srs_utest_rtc.cpp b/trunk/src/utest/srs_utest_rtc.cpp
index b40679008..9603c512c 100644
--- a/trunk/src/utest/srs_utest_rtc.cpp
+++ b/trunk/src/utest/srs_utest_rtc.cpp
@@ -62,7 +62,7 @@ VOID TEST(KernelRTCTest, RtpSTAPPayloadException)
     SrsAvcNaluType nalu_type = SrsAvcNaluTypeReserved;
     // Try to parse the NALU type for video decoder.
     if (!buf.empty()) {
-        nalu_type = SrsAvcNaluType((uint8_t)(buf.head()[0] & kNalTypeMask));
+        nalu_type = SrsAvcNaluTypeParse(buf.head()[0]);
     }
 
     EXPECT_TRUE(nalu_type == kStapA);