--- boost/format/parsing.hpp
+++ boost/format/parsing.hpp
@@ -19,6 +19,7 @@
 #include <boost/format/exceptions.hpp>
 #include <boost/throw_exception.hpp>
 #include <boost/assert.hpp>
+#include <boost/config.hpp>
 
 
 namespace boost {
@@ -267,6 +268,7 @@
         switch ( wrap_narrow(fac, *start, 0) ) {
         case 'X':
             fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
+            BOOST_FALLTHROUGH;
         case 'p': // pointer => set hex.
         case 'x':
             fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
@@ -280,6 +282,7 @@
 
         case 'E':
             fpar->fmtstate_.flags_ |=  std::ios_base::uppercase;
+            BOOST_FALLTHROUGH;
         case 'e':
             fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
             fpar->fmtstate_.flags_ |=  std::ios_base::scientific;
@@ -291,6 +294,7 @@
         case 'f':
             fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
             fpar->fmtstate_.flags_ |=  std::ios_base::fixed;
+            BOOST_FALLTHROUGH;
         case 'u':
         case 'd':
         case 'i':
--- ./boost/property_tree/detail/json_parser/standard_callbacks.hpp
+++ ./boost/property_tree/detail/json_parser/standard_callbacks.hpp
@@ -116,8 +116,8 @@
                 return *stack.back().t;
             }
             case object:
-                assert(false); // must start with string, i.e. call new_value
             case key: {
+                assert(l.k != object); // must start with string, i.e. call new_value
                 l.t->push_back(std::make_pair(key_buffer, Ptree()));
                 l.k = object;
                 layer nl = {leaf, &l.t->back().second};