diff --git a/configure.ac b/configure.ac
index b6811638d..9e04ff015 100644
--- a/configure.ac
+++ b/configure.ac
@@ -590,7 +590,10 @@ AC_ARG_ENABLE(aiglx,          AS_HELP_STRING([--enable-aiglx], [Build accelerate
                                 [AIGLX=yes])
 AX_TLS
 AC_ARG_ENABLE(glx-tls,        AS_HELP_STRING([--enable-glx-tls], [Build GLX with TLS support (default: auto)]),
-                                [GLX_USE_TLS=$enableval],
+                                [GLX_USE_TLS=$enableval
+                                 if test "x$GLX_USE_TLS" = "xyes" && test "${ac_cv_tls}" = "none" ; then
+                                   AC_MSG_ERROR([GLX with TLS support requested, but the compiler does not support it.])
+                                 fi],
                                 [GLX_USE_TLS=no
                                  if test "${ac_cv_tls}" != "none" ; then
                                    GLX_USE_TLS=yes
diff --git a/glx/glapi.c b/glx/glapi.c
index 209ae50c0..19576a775 100644
--- a/glx/glapi.c
+++ b/glx/glapi.c
@@ -184,11 +184,11 @@ static GLint NoOpUnused(void)
 /*@{*/
 #if defined(GLX_USE_TLS)
 
-PUBLIC __thread struct _glapi_table * _glapi_tls_Dispatch
+PUBLIC TLS struct _glapi_table * _glapi_tls_Dispatch
     __attribute__((tls_model("initial-exec")))
     = (struct _glapi_table *) __glapi_noop_table;
 
-PUBLIC __thread void * _glapi_tls_Context
+PUBLIC TLS void * _glapi_tls_Context
     __attribute__((tls_model("initial-exec")));
 
 PUBLIC const struct _glapi_table *_glapi_Dispatch = NULL;
diff --git a/glx/glapi.h b/glx/glapi.h
index 80b53aa92..dec8328cd 100644
--- a/glx/glapi.h
+++ b/glx/glapi.h
@@ -83,7 +83,7 @@ typedef void (*_glapi_warning_func)(void *ctx, const char *str, ...);
 const extern void *_glapi_Context;
 const extern struct _glapi_table *_glapi_Dispatch;
 
-extern __thread void * _glapi_tls_Context
+extern TLS void * _glapi_tls_Context
     __attribute__((tls_model("initial-exec")));
 
 # define GET_CURRENT_CONTEXT(C)  GLcontext *C = (GLcontext *) _glapi_tls_Context
diff --git a/glx/glthread.h b/glx/glthread.h
index 28793fcc7..140e2aa8e 100644
--- a/glx/glthread.h
+++ b/glx/glthread.h
@@ -233,7 +233,7 @@ _glthread_SetTSD(_glthread_TSD *, void *);
 
 #if defined(GLX_USE_TLS)
 
-extern __thread struct _glapi_table * _glapi_tls_Dispatch
+extern TLS struct _glapi_table * _glapi_tls_Dispatch
     __attribute__((tls_model("initial-exec")));
 
 #define GET_DISPATCH() _glapi_tls_Dispatch
diff --git a/include/dix-config.h.in b/include/dix-config.h.in
index fc93f3ec1..fd9ecced2 100644
--- a/include/dix-config.h.in
+++ b/include/dix-config.h.in
@@ -444,6 +444,9 @@
 /* Define to 1 if you have the `ffs' function. */
 #undef HAVE_FFS
 
+/* If the compiler supports a TLS storage class define it to that here */
+#undef TLS
+
 /* Correctly set _XSERVER64 for OSX fat binaries */
 #ifdef __APPLE__
 #include "dix-config-apple-verbatim.h"