--- linphone-3.10.2/configure.ac~	2016-08-30 16:20:09.000000000 +0200
+++ linphone-3.10.2/configure.ac	2018-09-26 15:05:58.553546486 +0200
@@ -898,11 +898,11 @@ if test x$enable_vcard != xfalse; then
 	if test "$found_vcard" = "no"; then
 		dnl Check the lib presence in case the PKG-CONFIG version is not found
 		AC_LANG_CPLUSPLUS
-		AC_CHECK_LIB(belcard, main, [BELCARD_LIBS+=" -lbelr -lbelcard"; found_vcard=yes], [foo=bar])
+		AC_CHECK_LIB(belcard, main, [BELCARD_LIBS="$BELCARD_LIBS -lbelr -lbelcard"; found_vcard=yes], [foo=bar])
 		AC_LANG_C
 	fi
 	if test "$found_vcard" = "yes"; then
-		BELCARD_CFLAGS+=" -DVCARD_ENABLED"
+		BELCARD_CFLAGS="$BELCARD_CFLAGS -DVCARD_ENABLED"
 		enable_vcard=true
 	else
 		if test x$enable_vcard = xtrue; then
@@ -931,12 +931,12 @@ if test x$enable_sqlite_storage != xfals
 	PKG_CHECK_MODULES(SQLITE3,[sqlite3 >= 3.6.0],[found_sqlite=yes],[found_sqlite=no])
 	if test "$found_sqlite" = "no"; then
 		dnl Check the lib presence in case the PKG-CONFIG version is not found
-		AC_CHECK_LIB(sqlite3, sqlite3_open, [SQLITE3_LIBS+=" -lsqlite3 "; found_sqlite=yes], [foo=bar])
+		AC_CHECK_LIB(sqlite3, sqlite3_open, [SQLITE3_LIBS="$SQLITE3_LIBS -lsqlite3 "; found_sqlite=yes], [foo=bar])
 	fi
 	if test "$found_sqlite" = "yes"; then
-		SQLITE3_CFLAGS+=" -DSQLITE_STORAGE_ENABLED"
+		SQLITE3_CFLAGS="$SQLITE3_CFLAGS -DSQLITE_STORAGE_ENABLED"
 		if test "$build_macos" = "yes" -o "$ios_found" = "yes"; then
-			SQLITE3_LIBS+=" -liconv"
+			SQLITE3_LIBS="$SQLITE3_LIBS -liconv"
 		fi
 		enable_msg_storage=true
 	else