diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index b5587fdfab37..3d7eae90a274 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2017-03-05  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/70266
+	* except.c (build_must_not_throw_expr): Perform the implicit
+	conversions on the condition.
+
 2017-03-03  Jason Merrill  <jason@redhat.com>
 
 	* mangle.c (mangle_decl): Check -Wnoexcept-type instead of
diff --git a/gcc/cp/except.c b/gcc/cp/except.c
index bfc32908aece..45d00cc0fc90 100644
--- a/gcc/cp/except.c
+++ b/gcc/cp/except.c
@@ -268,6 +268,9 @@ build_must_not_throw_expr (tree body, tree cond)
 
   if (cond && !value_dependent_expression_p (cond))
     {
+      cond = perform_implicit_conversion_flags (boolean_type_node, cond,
+						tf_warning_or_error,
+						LOOKUP_NORMAL);
       cond = cxx_constant_value (cond);
       if (integer_zerop (cond))
 	return body;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fcaacff3cc9e..26bfb0ac170b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-03-05  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/70266
+	* g++.dg/tm/pr70266.C: New.
+
 2017-03-05  Andre Vehreschild  <vehre@gcc.gnu.org>
             Alessandro Fanfarillo  <fanfarillo.gcc@gmail.com>
 
diff --git a/gcc/testsuite/g++.dg/tm/pr70266.C b/gcc/testsuite/g++.dg/tm/pr70266.C
new file mode 100644
index 000000000000..6f20afb51c69
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tm/pr70266.C
@@ -0,0 +1,8 @@
+// { dg-do compile { target c++11 } }
+// { dg-options "-fgnu-tm" }
+
+template < typename T > 
+int foo (int x, T t)
+{
+  return __transaction_atomic noexcept (foo) (1);  // { dg-error "cannot resolve" }
+}