diff --git a/configure b/configure
index 88087ad3b20d882fadcf69946344e64e4f5fbe22..68c01cbf74ffa6d5b5967a05fb4cea04140d6687 100755
--- a/configure
+++ b/configure
@@ -662,8 +662,8 @@ for opt do
   FFMPEG_CONFIGURATION="$FFMPEG_CONFIGURATION""$opt "
 done
 
-ENCODER_LIST=`grep 'register_avcodec(&[a-z0-9]*_encoder)' $source_path/libavcodec/allcodecs.c  | sed 's/.*&\(.*\)).*/\1/'`
-DECODER_LIST=`grep 'register_avcodec(&[a-z0-9]*_decoder)' $source_path/libavcodec/allcodecs.c  | sed 's/.*&\(.*\)).*/\1/'`
+ENCODER_LIST=`grep 'register_avcodec(&[a-z0-9_]*_encoder)' $source_path/libavcodec/allcodecs.c  | sed 's/.*&\(.*\)).*/\1/'`
+DECODER_LIST=`grep 'register_avcodec(&[a-z0-9_]*_decoder)' $source_path/libavcodec/allcodecs.c  | sed 's/.*&\(.*\)).*/\1/'`
 PARSER_LIST=`grep 'av_register_codec_parser(&[a-z]' $source_path/libavcodec/allcodecs.c  | sed 's/.*&\(.*\)).*/\1/'`
 MUXER_LIST=`grep 'av_register_output_format(&[a-z]' $source_path/libavformat/allformats.c  | sed 's/.*&\(.*\)).*/\1/'`
 DEMUXER_LIST=`grep 'av_register_input_format(&[a-z]' $source_path/libavformat/allformats.c  | sed 's/.*&\(.*\)).*/\1/'`