diff --git a/src/pvxs/data.h b/src/pvxs/data.h
index 3bb711c..294abf0 100644
--- a/src/pvxs/data.h
+++ b/src/pvxs/data.h
@@ -211,10 +211,8 @@ inline bool operator==(TypeCode lhs, TypeCode rhs) {
 inline bool operator!=(TypeCode lhs, TypeCode rhs) {
     return lhs.code!=rhs.code;
 }
-inline std::ostream& operator<<(std::ostream& strm, TypeCode c) {
-    strm<<c.name();
-    return strm;
-}
+PVXS_API
+std::ostream& operator<<(std::ostream& strm, TypeCode c);
 
 namespace impl {
 template<typename T>
diff --git a/src/type.cpp b/src/type.cpp
index 5f12129..fb5e194 100644
--- a/src/type.cpp
+++ b/src/type.cpp
@@ -94,7 +94,7 @@ StoreType TypeCode::storedAs() const
         return StoreType::Compound;
 
     } else {
-        throw std::logic_error("TypeCode::storedAs() not map");
+        throw std::logic_error(SB()<<"TypeCode::storedAs("<<(*this)<<") not map");
     }
 }
 
@@ -165,6 +165,17 @@ const char* TypeCode::name() const
     return "\?\?\?_t";
 }
 
+std::ostream& operator<<(std::ostream& strm, TypeCode c)
+{
+    auto name = c.name();
+    if(name[0]!='?') {
+        strm<<name;
+    } else {
+        strm<<"TypeCode(0x"<<std::hex<<(unsigned)c.code<<")";
+    }
+    return strm;
+}
+
 void Member::Helper::node_validate(const Member* parent, const std::string& id, TypeCode code)
 {
     if(!id.empty() && code.scalarOf()!=TypeCode::Struct && code.scalarOf()!=TypeCode::Union)