diff --git a/auxil/spicy b/auxil/spicy
index 8c7393744d..1650d875a8 160000
--- a/auxil/spicy
+++ b/auxil/spicy
@@ -1 +1 @@
-Subproject commit 8c7393744d2aa2e02f73f2b3dff4c2d5a46327d7
+Subproject commit 1650d875a87accce61bb9d8cde7f51f033280acf
diff --git a/cmake b/cmake
index 85c6f90f23..eede3aab03 160000
--- a/cmake
+++ b/cmake
@@ -1 +1 @@
-Subproject commit 85c6f90f238b5851edbd6b6962f44de34833a76c
+Subproject commit eede3aab03b80ade33a757f85dfc29f16a44499b
diff --git a/src/spicy/runtime-support.cc b/src/spicy/runtime-support.cc
index bf05925a4f..8140c1a0bf 100644
--- a/src/spicy/runtime-support.cc
+++ b/src/spicy/runtime-support.cc
@@ -66,38 +66,44 @@ static TypePtr findType(TypeTag tag, const std::string& ns, const std::string& i
     return type;
 }
 
-TypePtr rt::create_base_type(ZeekTypeTag tag) {
-    auto _ = hilti::rt::profiler::start("zeek/rt/create_base_type");
-    TypeTag ztag;
+static TypeTag zeekTypeForTag(rt::ZeekTypeTag tag) {
+    using namespace ::zeek::spicy::rt;
 
     switch ( tag ) {
-        case ZeekTypeTag::Addr: ztag = TYPE_ADDR; break;
-        case ZeekTypeTag::Any: ztag = TYPE_ANY; break;
-        case ZeekTypeTag::Bool: ztag = TYPE_BOOL; break;
-        case ZeekTypeTag::Count: ztag = TYPE_COUNT; break;
-        case ZeekTypeTag::Double: ztag = TYPE_DOUBLE; break;
-        case ZeekTypeTag::Enum: ztag = TYPE_ENUM; break;
-        case ZeekTypeTag::Error: ztag = TYPE_ERROR; break;
-        case ZeekTypeTag::File: ztag = TYPE_FILE; break;
-        case ZeekTypeTag::Func: ztag = TYPE_FUNC; break;
-        case ZeekTypeTag::List: ztag = TYPE_LIST; break;
-        case ZeekTypeTag::Int: ztag = TYPE_INT; break;
-        case ZeekTypeTag::Interval: ztag = TYPE_INTERVAL; break;
-        case ZeekTypeTag::Opaque: ztag = TYPE_OPAQUE; break;
-        case ZeekTypeTag::Pattern: ztag = TYPE_PATTERN; break;
-        case ZeekTypeTag::Port: ztag = TYPE_PORT; break;
-        case ZeekTypeTag::Record: ztag = TYPE_RECORD; break;
-        case ZeekTypeTag::String: ztag = TYPE_STRING; break;
-        case ZeekTypeTag::Subnet: ztag = TYPE_SUBNET; break;
-        case ZeekTypeTag::Table: ztag = TYPE_TABLE; break;
-        case ZeekTypeTag::Time: ztag = TYPE_TIME; break;
-        case ZeekTypeTag::Type: ztag = TYPE_TYPE; break;
-        case ZeekTypeTag::Vector: ztag = TYPE_VECTOR; break;
-        case ZeekTypeTag::Void: ztag = TYPE_VOID; break;
+        case ZeekTypeTag::Addr: return TYPE_ADDR;
+        case ZeekTypeTag::Any: return TYPE_ANY;
+        case ZeekTypeTag::Bool: return TYPE_BOOL;
+        case ZeekTypeTag::Count: return TYPE_COUNT;
+        case ZeekTypeTag::Double: return TYPE_DOUBLE;
+        case ZeekTypeTag::Enum: return TYPE_ENUM;
+        case ZeekTypeTag::Error: return TYPE_ERROR;
+        case ZeekTypeTag::File: return TYPE_FILE;
+        case ZeekTypeTag::Func: return TYPE_FUNC;
+        case ZeekTypeTag::List: return TYPE_LIST;
+        case ZeekTypeTag::Int: return TYPE_INT;
+        case ZeekTypeTag::Interval: return TYPE_INTERVAL;
+        case ZeekTypeTag::Opaque: return TYPE_OPAQUE;
+        case ZeekTypeTag::Pattern: return TYPE_PATTERN;
+        case ZeekTypeTag::Port: return TYPE_PORT;
+        case ZeekTypeTag::Record: return TYPE_RECORD;
+        case ZeekTypeTag::String: return TYPE_STRING;
+        case ZeekTypeTag::Subnet: return TYPE_SUBNET;
+        case ZeekTypeTag::Table: return TYPE_TABLE;
+        case ZeekTypeTag::Time: return TYPE_TIME;
+        case ZeekTypeTag::Type: return TYPE_TYPE;
+        case ZeekTypeTag::Vector: return TYPE_VECTOR;
+        case ZeekTypeTag::Void: return TYPE_VOID;
         default: hilti::rt::cannot_be_reached();
     }
+}
 
-    return base_type(ztag);
+TypePtr rt::create_base_type(ZeekTypeTag tag) {
+    auto _ = hilti::rt::profiler::start("zeek/rt/create_base_type");
+    return base_type(zeekTypeForTag(tag));
+}
+
+std::string hilti::rt::detail::adl::to_string(const zeek::spicy::rt::ZeekTypeTag& v, detail::adl::tag /* unused */) {
+    return type_name(zeekTypeForTag(v));
 }
 
 TypePtr rt::create_enum_type(
diff --git a/src/spicy/runtime-support.h b/src/spicy/runtime-support.h
index 78d82d3897..b15b08449a 100644
--- a/src/spicy/runtime-support.h
+++ b/src/spicy/runtime-support.h
@@ -1326,4 +1326,7 @@ inline std::string to_string(const zeek::spicy::rt::ValTablePtr& v, detail::adl:
 inline std::string to_string(const zeek::spicy::rt::ValVectorPtr& v, detail::adl::tag /* unused */) {
     return "<Zeek vector>";
 }
+
+extern std::string to_string(const zeek::spicy::rt::ZeekTypeTag& v, detail::adl::tag /* unused */);
+
 } // namespace hilti::rt::detail::adl