diff --git a/Makefile.generating b/Makefile.generating
index 4495a37a663d9e7b39f2f11c3aa0af09e2739471..2e1c0c6c5dfc5b3bdb9ca7fc003397c3255386d3 100644
--- a/Makefile.generating
+++ b/Makefile.generating
@@ -116,7 +116,6 @@ $(MACHDEP_PATH)/local_machdep.ml: \
 	$(ECHO) "}"          >>$@
 	$(ECHO) \
 	  "let gccHas__builtin_va_list = $(HAVE_BUILTIN_VA_LIST)" >>$@
-	$(ECHO) "let __thread_is_keyword = $(THREAD_IS_KEYWORD)"  >>$@
 	$(ECHO) \
 	  "$@ generated. You may have this file merged into Frama-C by developers."
 	$(CHMOD_RO) $@
diff --git a/config.h.in b/config.h.in
index 50555d91ca212376c50d24b65acc856529d1887b..73665676f86fe0110fc5cb25369a8f6e820916a8 100644
--- a/config.h.in
+++ b/config.h.in
@@ -52,6 +52,4 @@
 
 #undef HAVE_BUILTIN_VA_LIST
 
-#undef THREAD_IS_KEYWORD
-
 #undef UNDERSCORE_NAME
diff --git a/configure.in b/configure.in
index 271ec0976f4a495721593b61955409e015f5e5c7..284e9f5cea3280ba307aa6962ea4ad07f207f5ca 100644
--- a/configure.in
+++ b/configure.in
@@ -518,15 +518,6 @@ if test "$HAVE_BUILTIN_VA_LIST" = "true" ;then
    AC_DEFINE_UNQUOTED(HAVE_BUILTIN_VA_LIST, 1)
 fi
 
-AC_MSG_CHECKING([if __thread is a keyword])
-AC_COMPILE_IFELSE([AC_LANG_SOURCE([int main(int __thread) { return 0; }])],
-                  THREAD_IS_KEYWORD=false,
-                  THREAD_IS_KEYWORD=true)
-AC_MSG_RESULT($THREAD_IS_KEYWORD)
-if test "$THREAD_IS_KEYWORD" = "true" ;then
-   AC_DEFINE_UNQUOTED(THREAD_IS_KEYWORD, 1)
-fi
-
 # Does gcc add underscores to identifiers to make assembly labels?
 # (I think MSVC always does)
 AC_MSG_CHECKING([if gcc adds underscores to assembly labels.])
@@ -1001,7 +992,6 @@ AC_SUBST(HAVE_STDLIB_H)
 AC_SUBST(HAVE_WCHAR_H)
 AC_SUBST(HAVE_PTRDIFF_H)
 AC_SUBST(HAVE_BUILTIN_VA_LIST)
-AC_SUBST(THREAD_IS_KEYWORD)
 AC_SUBST(UNDERSCORE_NAME)
 AC_SUBST(CYCLES_PER_USEC)
 AC_SUBST(LOCAL_MACHDEP)
diff --git a/doc/developer/advance.tex b/doc/developer/advance.tex
index 459e80d888a46cb31fd9c2fbb05cf238377adce0..637f4624afb5b34f9af6979fcc083ff52fe96f50 100644
--- a/doc/developer/advance.tex
+++ b/doc/developer/advance.tex
@@ -3399,7 +3399,6 @@ let my_machine =
   little_endian = true;
   underscore_name = false ;
   has__builtin_va_list = true;
-  __thread_is_keyword = true;
 }
 
 let () = File.new_machdep "my_machine" my_machine
diff --git a/share/Makefile.config.in b/share/Makefile.config.in
index 89352cdc64fde2da3fc8af58ec9bedf9b2c45c0f..5b485c09b90a8ca699170b6a3e6f649d48946a9a 100644
--- a/share/Makefile.config.in
+++ b/share/Makefile.config.in
@@ -149,7 +149,6 @@ EXE		?=@EXE@
 # Required by Cil
 UNDERSCORE_NAME ?=@UNDERSCORE_NAME@
 HAVE_BUILTIN_VA_LIST ?=@HAVE_BUILTIN_VA_LIST@
-THREAD_IS_KEYWORD ?=@THREAD_IS_KEYWORD@
 
 # test directories for ptests configuration
 # Non-plugin test directories containing some ML files to compile
diff --git a/share/machdep.c b/share/machdep.c
index 43caa42a4518daa1c158a031c1103d6c9d26ceb3..cd0035e3314d8bf929f5a2902bb0299b65a4a4d1 100644
--- a/share/machdep.c
+++ b/share/machdep.c
@@ -343,15 +343,6 @@ int main() {
 #endif
   }
 
-  // __thread_is_keyword
-  {
-#ifdef THREAD_IS_KEYWORD
-    printf("\t __thread_is_keyword = true;\n");
-#else
-    printf("\t __thread_is_keyword = false;\n");
-#endif
-  }
-
   // underscore_name
   {
 #ifdef UNDERSCORE_NAME
diff --git a/src/kernel_internals/parsing/clexer.mll b/src/kernel_internals/parsing/clexer.mll
index de31b52c9d6179cdb2d7fb033b4f3a3785654807..603bab87c565977c17eece7e50293bb4e86baaff 100644
--- a/src/kernel_internals/parsing/clexer.mll
+++ b/src/kernel_internals/parsing/clexer.mll
@@ -206,13 +206,28 @@ let init_lexicon _ =
       ("__builtin_va_arg", fun loc -> BUILTIN_VA_ARG loc);
       ("__builtin_types_compatible_p", fun loc -> BUILTIN_TYPES_COMPAT loc);
       ("__builtin_offsetof", fun loc -> BUILTIN_OFFSETOF loc);
-      (* On some versions of GCC __thread is a regular identifier *)
+      ("_Thread_local",
+       fun loc ->
+         if Kernel.C11.get () then THREAD_LOCAL loc
+         else begin
+           Kernel.(
+             warning
+               ~wkey:wkey_conditional_feature
+               "_Thread_local is a C11 keyword, use -c11 option to enable it");
+           IDENT "_Thread_local"
+         end);
+      (* We recognize __thread for GCC machdeps *)
       ("__thread",
-       (fun loc ->
-          if Cil.theMachine.Cil.theMachine.Cil_types.__thread_is_keyword then
-            THREAD loc
-          else
-            IDENT "__thread"));
+       fun loc ->
+         if Cil.gccMode () then
+           THREAD loc
+         else begin
+           Kernel.(
+             warning
+               ~wkey:wkey_conditional_feature
+               "__thread is a GCC extension, use a GCC-based machdep to enable it");
+           IDENT "__thread"
+         end);
       ("__FC_FILENAME__",
        (fun loc ->
           let filename =
diff --git a/src/kernel_internals/parsing/cparser.mly b/src/kernel_internals/parsing/cparser.mly
index 8613ec75b579545f53ec9600e5e5514081b87ae4..95a4c0e88dd64826296785b7eb21e683f74534c1 100644
--- a/src/kernel_internals/parsing/cparser.mly
+++ b/src/kernel_internals/parsing/cparser.mly
@@ -334,7 +334,7 @@ let in_ghost_block ?(battrs=[]) l =
 %token<Cabs.cabsloc> ENUM STRUCT TYPEDEF UNION
 %token<Cabs.cabsloc> SIGNED UNSIGNED LONG SHORT
 %token<Cabs.cabsloc> VOLATILE EXTERN STATIC CONST RESTRICT AUTO REGISTER
-%token<Cabs.cabsloc> THREAD
+%token<Cabs.cabsloc> THREAD THREAD_LOCAL
 %token<Cabs.cabsloc> GHOST
 
 %token<Cabs.cabsloc> SIZEOF ALIGNOF
@@ -1510,7 +1510,10 @@ attribute_nocv:
 |   DECLSPEC paren_attr_list_ne         { ("__declspec", $2), $1 }
 |   MSATTR                              { (fst $1, []), snd $1 }
                                         /* ISO 6.7.3 */
-|   THREAD                              { ("__thread",[]), $1 }
+|   THREAD                              { ("__thread", []), $1 }
+|   THREAD_LOCAL                        { ("__thread",
+                                           [make_expr (VARIABLE "c11")]),
+                                          $1 }
 ;
 
 attribute_nocv_list:
diff --git a/src/kernel_internals/runtime/machdeps.ml b/src/kernel_internals/runtime/machdeps.ml
index 6372ee264983ad85ec8bfa40d2d8b453c181cdc8..3c9da30d57534a6e73ebe343faebe911a21929a6 100644
--- a/src/kernel_internals/runtime/machdeps.ml
+++ b/src/kernel_internals/runtime/machdeps.ml
@@ -79,7 +79,6 @@ let x86_16 = {
   little_endian = true;
   underscore_name = true ;
   has__builtin_va_list = true;
-  __thread_is_keyword = true;
 }
 
 let gcc_x86_16 = { x86_16 with
@@ -120,7 +119,6 @@ let x86_32 = {
   little_endian = true;
   underscore_name = false ;
   has__builtin_va_list = true;
-  __thread_is_keyword = true;
 }
 
 let gcc_x86_32 = { x86_32 with
@@ -161,7 +159,6 @@ let x86_64 = {
   little_endian = true;
   underscore_name = false ;
   has__builtin_va_list = true;
-  __thread_is_keyword = true;
 }
 
 let gcc_x86_64 = { x86_64 with
@@ -202,7 +199,6 @@ let ppc_32 = {
   little_endian = false;
   underscore_name = false ;
   has__builtin_va_list = true;
-  __thread_is_keyword = true;
 }
 
 let msvc_x86_64 = {
@@ -240,5 +236,4 @@ let msvc_x86_64 = {
   little_endian = true;
   underscore_name = false ;
   has__builtin_va_list = false;
-  __thread_is_keyword = false;
 }
diff --git a/src/kernel_internals/typing/cabs2cil.ml b/src/kernel_internals/typing/cabs2cil.ml
index de0e67072492daa5af65815d4cff643da90a7455..2b0157f69b5bb35fd22301b642da63030e968430 100644
--- a/src/kernel_internals/typing/cabs2cil.ml
+++ b/src/kernel_internals/typing/cabs2cil.ml
@@ -4812,6 +4812,14 @@ and makeVarInfoCabs
                                        we do it afterwards *)
       bt (A.PARENTYPE(attrs, ndt, a)) in
   (*Format.printf "Got yp:%a->%a(%a)@." d_type bt d_type vtype d_attrlist nattr;*)
+  if hasAttribute "thread" nattr then begin
+    let wkey = Kernel.wkey_inconsistent_specifier in
+    let source = fst ldecl in
+    if isFunctionType vtype then
+      Kernel.warning ~wkey ~source "only objects can be thread-local"
+    else if not isglobal && (sto = NoStorage || sto = Register) then
+      Kernel.warning ~wkey ~source "a local object cannot be thread-local";
+  end;
   if not isgenerated && ghost then begin
     if hasAttribute "ghost" (Cil.typeAttrs vtype) then
       Kernel.warning
@@ -9125,6 +9133,11 @@ and doDecl local_env (isglobal: bool) : A.definition -> chunk = function
       let ftyp, funattr =
         doType local_env.is_ghost false
           (AttrName false) bt (A.PARENTYPE(attrs, dt, a)) in
+      if hasAttribute "thread" funattr then begin
+        let wkey = Kernel.wkey_inconsistent_specifier in
+        let source = fst funloc in
+        Kernel.warning ~wkey ~source "only objects can be thread-local"
+      end;
       (* Format.printf "Attrs are %a@." d_attrlist funattr; *)
       Cil.update_var_type !currentFunctionFDEC.svar ftyp;
       !currentFunctionFDEC.svar.vattr <- funattr;
diff --git a/src/kernel_services/ast_data/cil_types.mli b/src/kernel_services/ast_data/cil_types.mli
index 9ad9fdb7a7684514813a0b79fee5116fcd7ab814..386affd6ea5a7f05d26205a6500e33fda3bfe00d 100644
--- a/src/kernel_services/ast_data/cil_types.mli
+++ b/src/kernel_services/ast_data/cil_types.mli
@@ -1912,7 +1912,6 @@ type mach = {
   little_endian: bool; (* whether the machine is little endian *)
   alignof_aligned: int (* Alignment of a type with aligned attribute *);
   has__builtin_va_list: bool (* Whether [__builtin_va_list] is a known type *);
-  __thread_is_keyword: bool (* Whether [__thread] is a keyword *);
   compiler: string;       (* Compiler being used. Currently recognized names
                              are 'gcc', 'msvc' and 'generic'. *)
   cpp_arch_flags: string list;  (* Architecture-specific flags to be given to
diff --git a/src/kernel_services/ast_printing/cil_printer.ml b/src/kernel_services/ast_printing/cil_printer.ml
index 085144c8958e90e32ddf4d935a75bc010c1dd2f3..4d3312bae1154f6a0a2ba915bb467a9e8db4e179 100644
--- a/src/kernel_services/ast_printing/cil_printer.ml
+++ b/src/kernel_services/ast_printing/cil_printer.ml
@@ -2056,6 +2056,9 @@ class cil_printer () = object (self)
        | "const", [] -> self#pp_keyword fmt "const"; false
        (* Put the aconst inside the attribute list *)
        | "aconst", [] when not (Cil.msvcMode ()) -> fprintf fmt "__const__"; true
+       | "thread", [ ACons ("c11",[]) ]
+         when not state.print_cil_as_is ->
+         fprintf fmt "_Thread_local"; false
        | "thread", [] when not (Cil.msvcMode ()) -> fprintf fmt "__thread"; false
        | "volatile", [] -> self#pp_keyword fmt "volatile"; false
        | "ghost", [] -> self#pp_keyword fmt "\\ghost"; false
diff --git a/src/kernel_services/ast_printing/cil_types_debug.ml b/src/kernel_services/ast_printing/cil_types_debug.ml
index 0b4be0a9ac93ec2a8d93fb8a07047eaf2ff7a62e..bf24ded49429a4dc0425d3d22e954df4c4835082 100644
--- a/src/kernel_services/ast_printing/cil_types_debug.ml
+++ b/src/kernel_services/ast_printing/cil_types_debug.ml
@@ -1058,7 +1058,7 @@ let pp_mach fmt mach =
      alignof_ptr=%a;alignof_float=%a;alignof_double=%a;alignof_longdouble=%a;\
      alignof_str=%a;alignof_fun=%a;char_is_unsigned=%a;underscore_name=%a;\
      const_string_literals=%a;little_endian=%a;alignof_aligned=%a;\
-     has__builtin_va_list=%a;__thread_is_keyword=%a;compiler=%a;\
+     has__builtin_va_list=%a;compiler=%a;\
      cpp_arch_flags=%a;version=%a}"
     pp_int mach.sizeof_short
     pp_int mach.sizeof_int
@@ -1089,7 +1089,6 @@ let pp_mach fmt mach =
     pp_bool mach.little_endian
     pp_int mach.alignof_aligned
     pp_bool mach.has__builtin_va_list
-    pp_bool mach.__thread_is_keyword
     pp_string mach.compiler
     (pp_list pp_string) mach.cpp_arch_flags
     pp_string mach.version
diff --git a/src/kernel_services/ast_queries/file.ml b/src/kernel_services/ast_queries/file.ml
index a1635dcd9dfa7ffa5f361137529f12c97e9eabb2..8d061af580a6862e260bb5932843ae6629f7e09e 100644
--- a/src/kernel_services/ast_queries/file.ml
+++ b/src/kernel_services/ast_queries/file.ml
@@ -296,8 +296,6 @@ let print_machdep fmt (m : Cil_types.mach) =
       (if m.underscore_name then "have" else "have no") ;
     Format.fprintf fmt "   compiler %s builtin __va_list@\n"
       (if m.has__builtin_va_list then "has" else "has not") ;
-    Format.fprintf fmt "   compiler %s __head as a keyword@\n"
-      (if m.__thread_is_keyword then "uses" else "does not use") ;
   end
 
 module DatatypeMachdep = Datatype.Make_with_collections(struct
diff --git a/src/kernel_services/plugin_entry_points/kernel.ml b/src/kernel_services/plugin_entry_points/kernel.ml
index da63179bf0fa0632cd2a51a10eafeff0dc914419..0d5cfc8f14bd3213c0d186142b7ed97f41605dd9 100644
--- a/src/kernel_services/plugin_entry_points/kernel.ml
+++ b/src/kernel_services/plugin_entry_points/kernel.ml
@@ -156,6 +156,9 @@ let wkey_incompatible_types_call =
 let wkey_incompatible_pointer_types =
   register_warn_category "typing:incompatible-pointer-types"
 
+let wkey_inconsistent_specifier =
+  register_warn_category "typing:inconsistent-specifier"
+
 let wkey_int_conversion =
   register_warn_category "typing:int-conversion"
 
diff --git a/src/kernel_services/plugin_entry_points/kernel.mli b/src/kernel_services/plugin_entry_points/kernel.mli
index d39ea5ecc84ccf582c169925714bb6f935de2049..c9dae9c7fd2a8eb422b6976f2bce1c8bf15cf982 100644
--- a/src/kernel_services/plugin_entry_points/kernel.mli
+++ b/src/kernel_services/plugin_entry_points/kernel.mli
@@ -153,6 +153,8 @@ val wkey_incompatible_types_call: warn_category
 
 val wkey_incompatible_pointer_types: warn_category
 
+val wkey_inconsistent_specifier: warn_category
+
 val wkey_int_conversion: warn_category
 
 val wkey_cert_exp_46: warn_category
diff --git a/tests/misc/custom_machdep/custom_machdep.ml b/tests/misc/custom_machdep/custom_machdep.ml
index da8ee8cf9ba794bdadaf45f50673cb83af71dca5..8942b2b793acec940637c3194d331047d15762dd 100644
--- a/tests/misc/custom_machdep/custom_machdep.ml
+++ b/tests/misc/custom_machdep/custom_machdep.ml
@@ -34,7 +34,6 @@ let mach =
   little_endian = true;
   underscore_name = false ;
   has__builtin_va_list = true;
-  __thread_is_keyword = true;
 }
 
 let mach2 = { mach with compiler = "baz" }
diff --git a/tests/misc/oracle/print_machdep.res.oracle b/tests/misc/oracle/print_machdep.res.oracle
index 598e0004a0994ab05684b08dbc8412a5f4b96979..4902716c8fc08e7971dd7cee455314ab41f65599 100644
--- a/tests/misc/oracle/print_machdep.res.oracle
+++ b/tests/misc/oracle/print_machdep.res.oracle
@@ -17,4 +17,3 @@ Machine: gcc 4.0.3 - X86-32bits mode
    strings are const chars
    assembly names have no leading '_'
    compiler has builtin __va_list
-   compiler uses __head as a keyword
diff --git a/tests/syntax/machdep_char_unsigned.ml b/tests/syntax/machdep_char_unsigned.ml
index 494492e8be26863ab7f54f10bae93d75753bbbef..296683fbd7b36ade780bc74482aff8e5d99758f9 100644
--- a/tests/syntax/machdep_char_unsigned.ml
+++ b/tests/syntax/machdep_char_unsigned.ml
@@ -34,7 +34,6 @@ let md = {
 	 wchar_t = "int";
 	 ptrdiff_t = "int";
          has__builtin_va_list = true;
-         __thread_is_keyword = false;
   }
 
 let () =
diff --git a/tests/syntax/oracle/thread.res.oracle b/tests/syntax/oracle/thread.res.oracle
new file mode 100644
index 0000000000000000000000000000000000000000..057e0bcc95de15188f4e85ddaa6cb038c86be9b7
--- /dev/null
+++ b/tests/syntax/oracle/thread.res.oracle
@@ -0,0 +1,39 @@
+[kernel] Parsing tests/syntax/thread.i (no preprocessing)
+[kernel:typing:inconsistent-specifier] tests/syntax/thread.i:10: Warning: 
+  only objects can be thread-local
+[kernel:typing:inconsistent-specifier] tests/syntax/thread.i:12: Warning: 
+  only objects can be thread-local
+[kernel:typing:inconsistent-specifier] tests/syntax/thread.i:15: Warning: 
+  a local object cannot be thread-local
+[kernel:typing:inconsistent-specifier] tests/syntax/thread.i:17: Warning: 
+  a local object cannot be thread-local
+/* Generated by Frama-C */
+ __thread int a;
+static  __thread int b;
+extern  __thread int c;
+
+ _Thread_local int d;
+ _Thread_local int bad(void);
+int bad(void)
+{
+  int __retres;
+  __retres = 0;
+  return __retres;
+}
+
+int main(void);
+
+int main(void)
+{
+  int __retres;
+   _Thread_local int e = 1;
+  register  _Thread_local int g = 1;
+  a = 0;
+  b = 0;
+  c = 0;
+  d = 0;
+  __retres = 0;
+  return __retres;
+}
+
+
diff --git a/tests/syntax/thread.i b/tests/syntax/thread.i
new file mode 100644
index 0000000000000000000000000000000000000000..9cbb150145707a58775d960f1efada95ef0b9d1c
--- /dev/null
+++ b/tests/syntax/thread.i
@@ -0,0 +1,23 @@
+/* run.config
+   STDOPT: +"-machdep gcc_x86_32 -c11"
+ */
+
+__thread int a;
+static __thread int b;
+extern __thread int c;
+_Thread_local int d;
+
+_Thread_local int bad() { return 0; } // KO
+
+_Thread_local int bad_also(void); // KO
+
+int main() {
+  _Thread_local int e = 1; // KO: e is neither extern nor static
+  static _Thread_local int f = 0; // OK
+  register _Thread_local int g = 1; // KO
+  a = 0;
+  b = 0;
+  c = 0;
+  d = 0;
+  return 0;
+}