diff --git a/Jamfile b/Jamfile
index 700526b6..b68cdccd 100644
--- a/Jamfile
+++ b/Jamfile
@@ -9,10 +9,11 @@
 
 import ../config/checks/config : requires ;
 
-# These make sure we only build
-# on C++11 or later toolchains.
+# These make sure we only build on
+# compatible C++11 or later toolchains.
 constant c11-requires :
     [ requires
+    cxx11_alignas
     cxx11_constexpr
     cxx11_decltype
     cxx11_hdr_tuple
diff --git a/meta/explicit-failures-markup.xml b/meta/explicit-failures-markup.xml
index 2e8c4073..2255de4d 100644
--- a/meta/explicit-failures-markup.xml
+++ b/meta/explicit-failures-markup.xml
@@ -7,6 +7,7 @@
             <toolset name="*gnu98"/>
             <toolset name="*c++0x"/>
             <toolset name="*gnu0x"/>
+            <toolset name="gcc-4.7*"/>
             <toolset name="msvc-7.1"/>
             <toolset name="msvc-8.*"/>
             <toolset name="msvc-9.*"/>