diff --git a/lib/modules/Protocols.pmod/SNMP.pmod/protocol.pike b/lib/modules/Protocols.pmod/SNMP.pmod/protocol.pike
index fab879b9b9f33d11980eadc56c8b0eb7ba61ac6d..cdef4a9985e5681d5d00af30a7a775b9288d676a 100644
--- a/lib/modules/Protocols.pmod/SNMP.pmod/protocol.pike
+++ b/lib/modules/Protocols.pmod/SNMP.pmod/protocol.pike
@@ -24,23 +24,25 @@ inherit Stdio.UDP : snmp;
 
 import Standards.ASN1.Types;
 
+#define U(x) make_combined_tag(0, (x))
+
 protected mapping snmp_type_proc =
   ([
     // from RFC-1065 :
-    64 : OctetString, // ipaddress
-    65 : Integer,     // counter
-    66 : Integer,     // gauge
-    67 : Integer,     // timeticks
-    68 : OctetString, // opaque
+    U(64) : OctetString, // ipaddress
+    U(65) : Integer,     // counter
+    U(66) : Integer,     // gauge
+    U(67) : Integer,     // timeticks
+    U(68) : OctetString, // opaque
 
     // v2
-    70 : Integer,     // counter64
+    U(70) : Integer,     // counter64
 
     // context PDU
-    128 : Sequence,
-    129 : Sequence,
-    130 : Sequence,
-    131 : Sequence,
+    U(128) : Sequence,
+    U(129) : Sequence,
+    U(130) : Sequence,
+    U(131) : Sequence,
   ]);
 
 
diff --git a/lib/modules/Standards.pmod/ASN1.pmod/Decode.pmod b/lib/modules/Standards.pmod/ASN1.pmod/Decode.pmod
index 7d0e8841d33a01619e0adea12a0c7b2654218757..e936ecfb1dc2b1a1cf843c98b06a2d4f3336dd55 100644
--- a/lib/modules/Standards.pmod/ASN1.pmod/Decode.pmod
+++ b/lib/modules/Standards.pmod/ASN1.pmod/Decode.pmod
@@ -207,8 +207,11 @@ mapping(int:program(.Types.Object)) universal_types =
 //!   a DER encoded object
 //!
 //! @param types
-//!   An optional set of application-specific types.
-//!   This set is used to extend @[universal_types].
+//!   An optional set of application-specific types. Should map
+//!   combined tag numbers to classes from or derived from
+//!   @[Standards.ASN1.Types]. Combined tag numbers may be generated
+//!   using @[Standards.ASN1.Types.make_combined_tag]. This set is
+//!   used to extend @[universal_types].
 //!
 //! @returns
 //!   an object from @[Standards.ASN1.Types] or