diff --git a/pgtype/pgtype.go b/pgtype/pgtype.go
index 75934ced..3244b504 100644
--- a/pgtype/pgtype.go
+++ b/pgtype/pgtype.go
@@ -344,10 +344,12 @@ func NewMap() *Map {
 	registerDefaultPgTypeVariants("int8", "_int8", int64(0))
 
 	// Integer types that do not have a direct match to a PostgreSQL type
+	registerDefaultPgTypeVariants("int8", "_int8", int8(0))
+	registerDefaultPgTypeVariants("int8", "_int8", int(0))
+	registerDefaultPgTypeVariants("int8", "_int8", uint8(0))
 	registerDefaultPgTypeVariants("int8", "_int8", uint16(0))
 	registerDefaultPgTypeVariants("int8", "_int8", uint32(0))
 	registerDefaultPgTypeVariants("int8", "_int8", uint64(0))
-	registerDefaultPgTypeVariants("int8", "_int8", int(0))
 	registerDefaultPgTypeVariants("int8", "_int8", uint(0))
 
 	registerDefaultPgTypeVariants("float4", "_float4", float32(0))
@@ -355,12 +357,46 @@ func NewMap() *Map {
 
 	registerDefaultPgTypeVariants("bool", "_bool", false)
 	registerDefaultPgTypeVariants("timestamptz", "_timestamptz", time.Time{})
+	registerDefaultPgTypeVariants("interval", "_interval", time.Duration(0))
 	registerDefaultPgTypeVariants("text", "_text", "")
 	registerDefaultPgTypeVariants("bytea", "_bytea", []byte(nil))
 
 	registerDefaultPgTypeVariants("inet", "_inet", net.IP{})
 	registerDefaultPgTypeVariants("cidr", "_cidr", net.IPNet{})
 
+	// pgtype provided structs
+	registerDefaultPgTypeVariants("varbit", "_varbit", Bits{})
+	registerDefaultPgTypeVariants("bool", "_bool", Bool{})
+	registerDefaultPgTypeVariants("box", "_box", Box{})
+	registerDefaultPgTypeVariants("circle", "_circle", Circle{})
+	registerDefaultPgTypeVariants("date", "_date", Date{})
+	registerDefaultPgTypeVariants("daterange", "_daterange", Daterange{})
+	registerDefaultPgTypeVariants("float4", "_float4", Float4{})
+	registerDefaultPgTypeVariants("float8", "_float8", Float8{})
+	registerDefaultPgTypeVariants("float8range", "_float8range", Float8range{})
+	registerDefaultPgTypeVariants("inet", "_inet", Inet{})
+	registerDefaultPgTypeVariants("int2", "_int2", Int2{})
+	registerDefaultPgTypeVariants("int4", "_int4", Int4{})
+	registerDefaultPgTypeVariants("int4range", "_int4range", Int4range{})
+	registerDefaultPgTypeVariants("int8", "_int8", Int8{})
+	registerDefaultPgTypeVariants("int8range", "_int8range", Int8range{})
+	registerDefaultPgTypeVariants("interval", "_interval", Interval{})
+	registerDefaultPgTypeVariants("line", "_line", Line{})
+	registerDefaultPgTypeVariants("lseg", "_lseg", Lseg{})
+	registerDefaultPgTypeVariants("numeric", "_numeric", Numeric{})
+	registerDefaultPgTypeVariants("numrange", "_numrange", Numrange{})
+	registerDefaultPgTypeVariants("path", "_path", Path{})
+	registerDefaultPgTypeVariants("point", "_point", Point{})
+	registerDefaultPgTypeVariants("polygon", "_polygon", Polygon{})
+	registerDefaultPgTypeVariants("tid", "_tid", TID{})
+	registerDefaultPgTypeVariants("text", "_text", Text{})
+	registerDefaultPgTypeVariants("time", "_time", Time{})
+	registerDefaultPgTypeVariants("timestamp", "_timestamp", Timestamp{})
+	registerDefaultPgTypeVariants("timestamptz", "_timestamptz", Timestamptz{})
+	registerDefaultPgTypeVariants("tsrange", "_tsrange", Tsrange{})
+	registerDefaultPgTypeVariants("tstzrange", "_tstzrange", Tstzrange{})
+	registerDefaultPgTypeVariants("uuid", "_uuid", UUID{})
+
 	return m
 }
 
@@ -1181,13 +1217,13 @@ func (m *Map) PlanEncode(oid uint32, format int16, value interface{}) EncodePlan
 		if plan := dt.Codec.PlanEncode(m, oid, format, value); plan != nil {
 			return plan
 		}
+	}
 
-		for _, f := range m.TryWrapEncodePlanFuncs {
-			if wrapperPlan, nextValue, ok := f(value); ok {
-				if nextPlan := m.PlanEncode(oid, format, nextValue); nextPlan != nil {
-					wrapperPlan.SetNext(nextPlan)
-					return wrapperPlan
-				}
+	for _, f := range m.TryWrapEncodePlanFuncs {
+		if wrapperPlan, nextValue, ok := f(value); ok {
+			if nextPlan := m.PlanEncode(oid, format, nextValue); nextPlan != nil {
+				wrapperPlan.SetNext(nextPlan)
+				return wrapperPlan
 			}
 		}
 	}
diff --git a/values.go b/values.go
index 766074bd..0f34b6a6 100644
--- a/values.go
+++ b/values.go
@@ -30,9 +30,13 @@ func convertSimpleArgument(m *pgtype.Map, arg interface{}) (interface{}, error)
 		return nil, nil
 	}
 
+	if dv, ok := arg.(driver.Valuer); ok {
+		return dv.Value()
+	}
+
+	// All these could be handled by m.Encode below. However, that transforms the argument to a string. That could change
+	// the type of the argument. e.g. '42' instead of 42. So standard types are special cased.
 	switch arg := arg.(type) {
-	case driver.Valuer:
-		return arg.Value()
 	case float32:
 		return float64(arg), nil
 	case float64: