diff --git a/CHANGELOG.md b/CHANGELOG.md
index 54c53d79..25063c6b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,10 @@ different versioning scheme, following the Haskell community's
 
 * When Unicode conversion fails during JSON deserialization to wstring, a
   bond::CoreException is now thrown instead of a Boost exception.
+* When SimpleJSON deserializes a map key with no matching value, a
+  bond::CoreException is now thrown.
+* When SimpleJSON deserializes a map key of non-primitive type, a
+  bond::CoreException is now thrown.
 
 ### C# ###
 
diff --git a/cpp/inc/bond/core/detail/string_stream.h b/cpp/inc/bond/core/detail/string_stream.h
index ddadaaf6..59103222 100644
--- a/cpp/inc/bond/core/detail/string_stream.h
+++ b/cpp/inc/bond/core/detail/string_stream.h
@@ -41,7 +41,8 @@ public:
         return *this;
     }
 
-    basic_string_stream& operator<<(const std::string& str)
+    template<typename T, typename A>
+    basic_string_stream& operator<<(const std::basic_string<char, T, A>& str)
     {
         write(str.begin(), str.end());
         return *this;
diff --git a/cpp/inc/bond/core/exception.h b/cpp/inc/bond/core/exception.h
index 700f59b1..d32de91a 100644
--- a/cpp/inc/bond/core/exception.h
+++ b/cpp/inc/bond/core/exception.h
@@ -5,6 +5,8 @@
 
 #include "detail/string_stream.h"
 #include <bond/core/bond_types.h>
+#include <boost/locale/encoding_utf.hpp>
+#include <boost/utility/enable_if.hpp>
 
 #define BOND_THROW(x, y)  throw x((::bond::detail::basic_string_stream<1024>() << y).content());
 
@@ -55,26 +57,65 @@ BOND_NORETURN inline void MergerContainerException(uint32_t payload, uint32_t ob
 }
 
 
+BOND_NORETURN inline void InvalidKeyTypeException()
+{
+    BOND_THROW(CoreException,
+        "Map key type not valid");
+}
+
+
+namespace detail
+{
+    template <typename Key>
+    BOND_NORETURN inline void ElementNotFoundExceptionHelper(
+        const Key& key,
+        typename boost::enable_if<is_wstring<Key>>::type* = nullptr)
+    {
+        try
+        {
+            BOND_THROW(CoreException,
+                "Map element not found: key: " <<
+                    boost::locale::conv::utf_to_utf<char>(
+                        string_data(key),
+                        string_data(key) + string_length(key),
+                        boost::locale::conv::stop));
+        }
+        catch (boost::locale::conv::conversion_error &)
+        {
+            BOND_THROW(CoreException, "Map element not found: key: <bad wstring>");
+        }
+    }
+
+    template <typename Key>
+    BOND_NORETURN inline void ElementNotFoundExceptionHelper(
+        const Key& key,
+        typename boost::disable_if<is_wstring<Key>>::type* = nullptr)
+    {
+        BOND_THROW(CoreException,
+            "Map element not found: key: " << key);
+    }
+}
+
+
 template <typename Key>
 BOND_NORETURN inline void ElementNotFoundException(const Key& key)
 {
-    BOND_THROW(CoreException,
-          "Map element not found: key: " << key);
+    detail::ElementNotFoundExceptionHelper(key);
 }
 
 
 BOND_NORETURN inline void UnknownProtocolException()
 {
     BOND_THROW(CoreException,
-          "Unmarshaling failed: unsupported protocol"); 
+          "Unmarshaling failed: unsupported protocol");
 }
 
 
 BOND_NORETURN inline void UnknownProtocolException(uint16_t magic)
 {
     BOND_THROW(CoreException,
-          "Unsupported protocol: " 
-          << (char)(magic & 0xFF) << (char)(magic >> 8)); 
+          "Unsupported protocol: "
+          << (char)(magic & 0xFF) << (char)(magic >> 8));
 }
 
 
@@ -87,14 +128,14 @@ BOND_NORETURN inline void NothingException()
 
 BOND_NORETURN inline void InvalidEnumValueException(const char* value, const char* enum_)
 {
-    BOND_THROW(bond::CoreException, 
+    BOND_THROW(bond::CoreException,
         "Unexpected value " << value << " for enum " << enum_);
 }
 
 
 BOND_NORETURN inline void InvalidEnumValueException(int32_t value, const char* enum_)
 {
-    BOND_THROW(bond::CoreException, 
+    BOND_THROW(bond::CoreException,
         "Unexpected value " << value << " for enum " << enum_);
 }
 
@@ -106,7 +147,7 @@ BOND_NORETURN inline void RapidJsonException(const char* error, size_t offset)
 }
 
 
-BOND_NORETURN inline void UnicodeConversionException(void)
+BOND_NORETURN inline void UnicodeConversionException()
 {
     BOND_THROW(CoreException,
         "Unicode conversion exception");
@@ -135,8 +176,8 @@ BOND_NORETURN
 inline void StructBaseDifferentException(const StructDef& src,
                                          const StructDef& dst)
 {
-    BOND_THROW(SchemaValidateException, 
-        "Schemas are incompatible; struct base different: " 
+    BOND_THROW(SchemaValidateException,
+        "Schemas are incompatible; struct base different: "
         << src.metadata.name << ", " << dst.metadata.name);
 }
 
@@ -145,8 +186,8 @@ BOND_NORETURN
 inline void RequiredFieldMissingException(const StructDef& s_dst,
                                           const FieldDef& f_dst)
 {
-    BOND_THROW(SchemaValidateException, 
-        "Schemas are incompatible; required field missing: " 
+    BOND_THROW(SchemaValidateException,
+        "Schemas are incompatible; required field missing: "
         << s_dst.metadata.name << "::" << f_dst.metadata.name);
 }
 
@@ -157,9 +198,9 @@ inline void OptionalToRequiredException(const StructDef& s_src,
                                         const FieldDef& f_src,
                                         const FieldDef& f_dst)
 {
-    BOND_THROW(SchemaValidateException, 
-        "Schemas are incompatible; required modifier removed: " 
-        << s_src.metadata.name << "::" << f_src.metadata.name << ", " 
+    BOND_THROW(SchemaValidateException,
+        "Schemas are incompatible; required modifier removed: "
+        << s_src.metadata.name << "::" << f_src.metadata.name << ", "
         << s_dst.metadata.name << "::" << f_dst.metadata.name);
 }
 
@@ -170,16 +211,16 @@ inline void FieldTypeIncompatibleException(const StructDef& s_src,
                                            const FieldDef& f_src,
                                            const FieldDef& f_dst)
 {
-    BOND_THROW(SchemaValidateException, 
-        "Schemas are incompatible; field types incompatible: " 
-        << s_src.metadata.name << "::" << f_src.metadata.name << ", " 
+    BOND_THROW(SchemaValidateException,
+        "Schemas are incompatible; field types incompatible: "
+        << s_src.metadata.name << "::" << f_src.metadata.name << ", "
         << s_dst.metadata.name << "::" << f_dst.metadata.name);
 }
 
 
 BOND_NORETURN inline void UnknownSchemaDefException(uint16_t id)
 {
-    BOND_THROW(SchemaValidateException, 
+    BOND_THROW(SchemaValidateException,
         "Failed to validate schema compatibility; "
         "SchemaDef contains unknown field: " << id);
 }
diff --git a/cpp/inc/bond/protocol/simple_json_reader_impl.h b/cpp/inc/bond/protocol/simple_json_reader_impl.h
index 34596e02..a42afc5e 100644
--- a/cpp/inc/bond/protocol/simple_json_reader_impl.h
+++ b/cpp/inc/bond/protocol/simple_json_reader_impl.h
@@ -150,8 +150,19 @@ DeserializeMap(X& var, BondDataType keyType, const T& element, SimpleJsonReader<
         {
             detail::Read(*it, key);
         }
+        else
+        {
+            bond::InvalidKeyTypeException();
+        }
 
-        SimpleJsonReader<Buffer> input(reader, *++it);
+        ++it;
+
+        if (it == end)
+        {
+            bond::ElementNotFoundException(key);
+        }
+
+        SimpleJsonReader<Buffer> input(reader, *it);
 
         if (value_type.ComplexTypeMatch(*it))
             detail::MakeValue(input, element).template Deserialize<Protocols>(mapped_at(var, key));