Index: audacity-Audacity-2.3.3/m4/audacity_checklib_libflac.m4
===================================================================
--- audacity-Audacity-2.3.3.orig/m4/audacity_checklib_libflac.m4	2019-11-15 13:14:55.000000000 +0200
+++ audacity-Audacity-2.3.3/m4/audacity_checklib_libflac.m4	2020-02-02 15:41:14.847457491 +0200
@@ -13,21 +13,21 @@ AC_DEFUN([AUDACITY_CHECKLIB_LIBFLAC], [
 
    dnl See if FLAC is installed in the system
 
-   PKG_CHECK_MODULES([FLAC], [flac >= 1.3.0 flac++ >= 1.3.0],
+   PKG_CHECK_MODULES([FLAC], [flac >= 1.3.1 flac++ >= 1.3.1],
                      [LIBFLAC_SYSTEM_AVAILABLE="yes"],
                      [LIBFLAC_SYSTEM_AVAILABLE="no"])
 
-   dnl Check for flac < 1.3.0
+   dnl Check for flac < 1.3.1
    if test "$LIBFLAC_SYSTEM_AVAILABLE" = "no"; then
       PKG_CHECK_MODULES([FLAC], [flac flac++],
                         [LIBFLAC_SYSTEM_AVAILABLE="yes"],
                         [LIBFLAC_SYSTEM_AVAILABLE="no"])
-      dnl flac < 1.3.0 adds its own FLAC and FLAC++ subdirectories to the search
+      dnl flac < 1.3.1 adds its own FLAC and FLAC++ subdirectories to the search
       dnl path and ships a assert.h file there. This assert.h overwrites the
       dnl assert.h header from the C standard library. We need to strip /FLAC
       dnl and /FLAC++ from the include paths to make the assert.h from the C
       dnl standard library available again.
-      [FLAC_CFLAGS=$(echo "$FLAC_CFLAGS" | sed 's@-I\([^ ]*\)/FLAC\(++\)\? @-I\1 @g')]
+      [FLAC_CFLAGS=$(echo "$FLAC_CFLAGS" | sed 's|-I\([^ ]*\)/FLAC\(++\)\?[ ]*|-I\1 |g')]
    fi
 
    if test "$LIBFLAC_SYSTEM_AVAILABLE" = "yes"; then