diff --git a/m4/audacity_checklib_ffmpeg.m4 b/m4/audacity_checklib_ffmpeg.m4
index c5a671557..41030747b 100644
--- a/m4/audacity_checklib_ffmpeg.m4
+++ b/m4/audacity_checklib_ffmpeg.m4
@@ -73,6 +73,6 @@ AC_DEFUN([AUDACITY_CHECKLIB_FFMPEG], [
       AC_MSG_NOTICE([ffmpeg library is NOT available in the local tree])
    fi
    
-   FFMPEG_MIMETYPES="audio/aac;audio/mp4;audio/x-ms-wma;"
+   FFMPEG_MIMETYPES="audio/aac;audio/ac3;audio/mp4;audio/x-ms-wma;video/mpeg;"
 ])
 
diff --git a/m4/audacity_checklib_libflac.m4 b/m4/audacity_checklib_libflac.m4
index dc5b05f81..121176d6d 100644
--- a/m4/audacity_checklib_libflac.m4
+++ b/m4/audacity_checklib_libflac.m4
@@ -68,5 +68,7 @@ AC_DEFUN([AUDACITY_CHECKLIB_LIBFLAC], [
    else
       AC_MSG_NOTICE([FLAC libraries are NOT available in this source tree])
    fi
+
+   LIBFLAC_MIMETYPES="audio/flac;audio/x-flac;"
 ])
 
diff --git a/m4/audacity_checklib_libmad.m4 b/m4/audacity_checklib_libmad.m4
index 66f3b26bd..d92c90909 100644
--- a/m4/audacity_checklib_libmad.m4
+++ b/m4/audacity_checklib_libmad.m4
@@ -59,5 +59,6 @@ AC_DEFUN([AUDACITY_CHECKLIB_LIBMAD], [
       LIBMAD_LOCAL_AVAILABLE="no"
       AC_MSG_NOTICE([libmad libraries are NOT available in the local tree])
    fi
+   LIBMAD_MIMETYPES="audio/mpeg;"
 ])
 
diff --git a/m4/audacity_checklib_libsndfile.m4 b/m4/audacity_checklib_libsndfile.m4
index a4cb60e77..8d8c4fbf7 100644
--- a/m4/audacity_checklib_libsndfile.m4
+++ b/m4/audacity_checklib_libsndfile.m4
@@ -50,6 +50,6 @@ AC_DEFUN([AUDACITY_CHECKLIB_LIBSNDFILE], [
       LIBSNDFILE_LOCAL_AVAILABLE="no"
       AC_MSG_NOTICE([libsndfile libraries are NOT available in this source tree])
    fi
-
+   LIBSNDFILE_MIMETYPES="audio/basic;audio/x-aiff;audio/x-wav;"
 ])
 
diff --git a/m4/audacity_checklib_libvorbis.m4 b/m4/audacity_checklib_libvorbis.m4
index 09935f6ee..9cc82466e 100644
--- a/m4/audacity_checklib_libvorbis.m4
+++ b/m4/audacity_checklib_libvorbis.m4
@@ -64,5 +64,6 @@ AC_DEFUN([AUDACITY_CHECKLIB_LIBVORBIS], [
    else
       AC_MSG_NOTICE([Vorbis libraries are NOT available in this source tree])
    fi
+   LIBVORBIS_MIMETYPES="application/ogg;audio/x-vorbis+ogg;"
 ])