diff --git a/ChangeLog b/ChangeLog
index 96140db7..7ce26f3b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2009-12-22  Marcus Brinkmann  <marcus@g10code.de>
+
+	* configure.ac: Do not use echo -n.  Test for __thread.
+
 2009-12-17  Marcus Brinkmann  <marcus@g10code.de>
 
 	* configure.ac: Make largefile check more robust.
diff --git a/configure.ac b/configure.ac
index cb3db3d6..90df95f8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -34,7 +34,7 @@ min_automake_version="1.10"
 m4_define(my_version, [1.2.1])
 m4_define(my_issvn, [yes])
 
-m4_define([svn_revision], m4_esyscmd([echo -n $( (svn info 2>/dev/null \
+m4_define([svn_revision], m4_esyscmd([printf "%d" $( (svn info 2>/dev/null \
             || echo 'Revision: 0')|sed -n '/^Revision:/ {s/[^0-9]//gp;q;}')]))
 AC_INIT([gpgme], 
         [my_version[]m4_if(my_issvn,[yes],[-svn[]svn_revision])],
@@ -224,6 +224,17 @@ if test "$GCC" = yes; then
     fi
 fi
 
+# Only used for debugging, so no serious test needed (for actual
+# functionality you have to test libc as well, this only tests the
+# compiler).
+AC_CACHE_CHECK([for __thread],[gpgme_cv_tls_works],
+   AC_COMPILE_IFELSE([__thread int foo;],
+     gpgme_cv_tls_works=yes,gpgme_cv_tls_works=no))
+if test "$gpgme_cv_tls_works" = yes; then
+  AC_DEFINE(HAVE_TLS, [1], [Define if __thread is supported])
+fi
+
+
 # Checks for library functions.
 AC_FUNC_FSEEKO
 
diff --git a/src/ChangeLog b/src/ChangeLog
index 98de853f..4a83b93c 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2009-12-22  Marcus Brinkmann  <marcus@g10code.de>
+
+	* debug.c: Test for TLS, not __GNUC__
+
 2009-12-15  Marcus Brinkmann  <marcus@g10code.de>
 
 	* assuan-support.c (my_spawn): Calloc, not malloc, the fd_items.
diff --git a/src/debug.c b/src/debug.c
index 1471ff24..38e0cca6 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -55,7 +55,7 @@ static int debug_level;
 static FILE *errfp;
 
 
-#ifdef __GNUC__
+#ifdef HAVE_TLS
 #define FRAME_NR
 static __thread int frame_nr = 0;
 #endif