diff -up libsndfile-1.1.0/CMakeLists.txt.system-gsm libsndfile-1.1.0/CMakeLists.txt
--- libsndfile-1.1.0/CMakeLists.txt.system-gsm	2022-03-27 14:39:27.000000000 +0200
+++ libsndfile-1.1.0/CMakeLists.txt	2022-04-25 22:41:46.472440316 +0200
@@ -286,7 +286,6 @@ add_library (sndfile
 	src/double64.c
 	src/ima_adpcm.c
 	src/ms_adpcm.c
-	src/gsm610.c
 	src/dwvw.c
 	src/vox_adpcm.c
 	src/interleave.c
@@ -347,23 +346,6 @@ add_library (sndfile
 	src/mpeg.c
 	src/mpeg_decode.c
 	src/mpeg_l3_encode.c
-	src/GSM610/config.h
-	src/GSM610/gsm.h
-	src/GSM610/gsm610_priv.h
-	src/GSM610/add.c
-	src/GSM610/code.c
-	src/GSM610/decode.c
-	src/GSM610/gsm_create.c
-	src/GSM610/gsm_decode.c
-	src/GSM610/gsm_destroy.c
-	src/GSM610/gsm_encode.c
-	src/GSM610/gsm_option.c
-	src/GSM610/long_term.c
-	src/GSM610/lpc.c
-	src/GSM610/preprocess.c
-	src/GSM610/rpe.c
-	src/GSM610/short_term.c
-	src/GSM610/table.c
 	src/G72x/g72x.h
 	src/G72x/g72x_priv.h
 	src/G72x/g721.c
@@ -412,6 +394,7 @@ target_link_libraries (sndfile
 		$<$<BOOL:${HAVE_EXTERNAL_XIPH_LIBS}>:Opus::opus>
 		$<$<BOOL:${HAVE_MPEG}>:MPG123::libmpg123>
 		$<$<BOOL:${HAVE_MPEG}>:mp3lame::mp3lame>
+		-lgsm
 	)
 set_target_properties (sndfile PROPERTIES
 	PUBLIC_HEADER "${sndfile_HDRS}"
diff -up libsndfile-1.1.0/Makefile.am.system-gsm libsndfile-1.1.0/Makefile.am
--- libsndfile-1.1.0/Makefile.am.system-gsm	2022-03-27 10:55:12.000000000 +0200
+++ libsndfile-1.1.0/Makefile.am	2022-04-25 22:39:56.976112391 +0200
@@ -47,7 +47,6 @@ SYMBOL_FILES = src/Symbols.gnu-binutils
 
 EXTRA_DIST += src/config.h.in src/test_endswap.tpl src/test_endswap.def \
 	$(SYMBOL_FILES) src/create_symbols_file.py src/binheader_writef_check.py \
-	src/GSM610/README src/GSM610/COPYRIGHT src/GSM610/ChangeLog \
 	src/G72x/README src/G72x/README.original src/G72x/ChangeLog \
 	src/make-static-lib-hidden-privates.sh \
 	src/config.h.cmake
@@ -72,7 +71,7 @@ src_libsndfile_la_SOURCES = src/sndfile.
 	src/ogg.c src/ogg.h src/ogg_vorbis.c src/ogg_speex.c src/ogg_pcm.c src/ogg_opus.c src/ogg_vcomment.c src/ogg_vcomment.h \
 	src/common.h src/sfconfig.h src/sfendian.h src/wavlike.h src/sf_unistd.h src/chanmap.h src/mpeg.c
 nodist_src_libsndfile_la_SOURCES = $(nodist_include_HEADERS)
-src_libsndfile_la_LIBADD = src/GSM610/libgsm.la src/G72x/libg72x.la src/ALAC/libalac.la \
+src_libsndfile_la_LIBADD = -lgsm src/G72x/libg72x.la src/ALAC/libalac.la \
 	src/libcommon.la $(EXTERNAL_XIPH_LIBS) -lm $(MPEG_LIBS)
 EXTRA_src_libsndfile_la_DEPENDENCIES = $(SYMBOL_FILES)
 
@@ -91,17 +90,6 @@ src_test_main_SOURCES = src/test_main.c
 	src/test_binheader_writef.c src/test_nms_adpcm.c
 src_test_main_LDADD = src/libcommon.la
 
-##############
-# src/GSM610 #
-##############
-
-noinst_LTLIBRARIES += src/GSM610/libgsm.la
-src_GSM610_libgsm_la_SOURCES = src/GSM610/config.h src/GSM610/gsm.h src/GSM610/gsm610_priv.h \
-	src/GSM610/add.c src/GSM610/code.c src/GSM610/decode.c src/GSM610/gsm_create.c \
-	src/GSM610/gsm_decode.c src/GSM610/gsm_destroy.c src/GSM610/gsm_encode.c \
-	src/GSM610/gsm_option.c src/GSM610/long_term.c src/GSM610/lpc.c src/GSM610/preprocess.c \
-	src/GSM610/rpe.c src/GSM610/short_term.c src/GSM610/table.c
-
 ############
 # src/G72x #
 ############
diff -up libsndfile-1.1.0/src/gsm610.c.system-gsm libsndfile-1.1.0/src/gsm610.c
--- libsndfile-1.1.0/src/gsm610.c.system-gsm	2021-05-17 11:12:28.000000000 +0200
+++ libsndfile-1.1.0/src/gsm610.c	2022-04-25 22:37:21.059496852 +0200
@@ -27,7 +27,7 @@
 #include "sfendian.h"
 #include "common.h"
 #include "wavlike.h"
-#include "GSM610/gsm.h"
+#include <gsm.h>
 
 #define	GSM610_BLOCKSIZE		33
 #define	GSM610_SAMPLES			160
@@ -391,7 +391,8 @@ gsm610_seek	(SF_PRIVATE *psf, int UNUSED
 		psf_fseek (psf, psf->dataoffset, SEEK_SET) ;
 		pgsm610->blockcount = 0 ;
 
-		gsm_init (pgsm610->gsm_data) ;
+                gsm_destroy (pgsm610->gsm_data) ;
+                pgsm610->gsm_data = gsm_create () ;
 		if ((SF_CONTAINER (psf->sf.format)) == SF_FORMAT_WAV ||
 				(SF_CONTAINER (psf->sf.format)) == SF_FORMAT_W64)
 			gsm_option (pgsm610->gsm_data, GSM_OPT_WAV49, &true_flag) ;