diff --git a/libavcodec/h2645_parse.h b/libavcodec/h2645_parse.h
index 630235994e..3a60f3fb9b 100644
--- a/libavcodec/h2645_parse.h
+++ b/libavcodec/h2645_parse.h
@@ -90,4 +90,24 @@ int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,
  */
 void ff_h2645_packet_uninit(H2645Packet *pkt);
 
+static inline int get_nalsize(int nal_length_size, const uint8_t *buf,
+                              int buf_size, int *buf_index, void *logctx)
+{
+    int i, nalsize = 0;
+
+    if (*buf_index >= buf_size - nal_length_size) {
+        // the end of the buffer is reached, refill it
+        return AVERROR(EAGAIN);
+    }
+
+    for (i = 0; i < nal_length_size; i++)
+        nalsize = ((unsigned)nalsize << 8) | buf[(*buf_index)++];
+    if (nalsize <= 0 || nalsize > buf_size - *buf_index) {
+        av_log(logctx, AV_LOG_ERROR,
+               "Invalid nal size %d\n", nalsize);
+        return AVERROR_INVALIDDATA;
+    }
+    return nalsize;
+}
+
 #endif /* AVCODEC_H2645_PARSE_H */
diff --git a/libavcodec/h264_parser.c b/libavcodec/h264_parser.c
index 8abe05d41c..615884fdac 100644
--- a/libavcodec/h264_parser.c
+++ b/libavcodec/h264_parser.c
@@ -228,26 +228,6 @@ static int scan_mmco_reset(AVCodecParserContext *s, GetBitContext *gb,
     return 0;
 }
 
-static inline int get_avc_nalsize(H264ParseContext *p, const uint8_t *buf,
-                                  int buf_size, int *buf_index, void *logctx)
-{
-    int i, nalsize = 0;
-
-    if (*buf_index >= buf_size - p->nal_length_size) {
-        // the end of the buffer is reached, refill it
-        return AVERROR(EAGAIN);
-    }
-
-    for (i = 0; i < p->nal_length_size; i++)
-        nalsize = ((unsigned)nalsize << 8) | buf[(*buf_index)++];
-    if (nalsize <= 0 || nalsize > buf_size - *buf_index) {
-        av_log(logctx, AV_LOG_ERROR,
-               "AVC: nal size %d\n", nalsize);
-        return AVERROR_INVALIDDATA;
-    }
-    return nalsize;
-}
-
 /**
  * Parse NAL units of found picture and decode some basic information.
  *
@@ -288,7 +268,7 @@ static inline int parse_nal_units(AVCodecParserContext *s,
         int src_length, consumed, nalsize = 0;
 
         if (buf_index >= next_avc) {
-            nalsize = get_avc_nalsize(p, buf, buf_size, &buf_index, avctx);
+            nalsize = get_nalsize(p->nal_length_size, buf, buf_size, &buf_index, avctx);
             if (nalsize < 0)
                 break;
             next_avc = buf_index + nalsize;