diff --git a/config/config.go b/config/config.go
index f5e7db6bbc106..4798814c009f9 100644
--- a/config/config.go
+++ b/config/config.go
@@ -1033,8 +1033,7 @@ func (c *Config) addInput(name string, table *ast.Table) error {
 
 	// If the input has a SetParser function, then this means it can accept
 	// arbitrary types of input, so build the parser and set it.
-	switch t := input.(type) {
-	case parsers.ParserInput:
+	if t, ok := input.(parsers.ParserInput); ok {
 		parser, err := buildParser(name, table)
 		if err != nil {
 			return err
@@ -1042,8 +1041,7 @@ func (c *Config) addInput(name string, table *ast.Table) error {
 		t.SetParser(parser)
 	}
 
-	switch t := input.(type) {
-	case parsers.ParserFuncInput:
+	if t, ok := input.(parsers.ParserFuncInput); ok {
 		config, err := getParserConfig(name, table)
 		if err != nil {
 			return err
diff --git a/config/types.go b/config/types.go
index 3acf3d1d6019e..7c1c50b9e3690 100644
--- a/config/types.go
+++ b/config/types.go
@@ -14,9 +14,6 @@ type Duration time.Duration
 // Size is an int64
 type Size int64
 
-// Number is a float
-type Number float64
-
 // UnmarshalTOML parses the duration from the TOML config file
 func (d *Duration) UnmarshalTOML(b []byte) error {
 	var err error
@@ -56,20 +53,29 @@ func (d *Duration) UnmarshalTOML(b []byte) error {
 	return nil
 }
 
+func (d *Duration) UnmarshalText(text []byte) error {
+	return d.UnmarshalTOML(text)
+}
+
 func (s *Size) UnmarshalTOML(b []byte) error {
 	var err error
-	b = bytes.Trim(b, `'`)
+	if len(b) == 0 {
+		return nil
+	}
+	str := string(b)
+	if b[0] == '"' || b[0] == '\'' {
+		str, err = strconv.Unquote(str)
+		if err != nil {
+			return err
+		}
+	}
 
-	val, err := strconv.ParseInt(string(b), 10, 64)
+	val, err := strconv.ParseInt(str, 10, 64)
 	if err == nil {
 		*s = Size(val)
 		return nil
 	}
-	uq, err := strconv.Unquote(string(b))
-	if err != nil {
-		return err
-	}
-	val, err = units.ParseStrictBytes(uq)
+	val, err = units.ParseStrictBytes(str)
 	if err != nil {
 		return err
 	}
@@ -77,12 +83,6 @@ func (s *Size) UnmarshalTOML(b []byte) error {
 	return nil
 }
 
-func (n *Number) UnmarshalTOML(b []byte) error {
-	value, err := strconv.ParseFloat(string(b), 64)
-	if err != nil {
-		return err
-	}
-
-	*n = Number(value)
-	return nil
+func (s *Size) UnmarshalText(text []byte) error {
+	return s.UnmarshalTOML(text)
 }
diff --git a/config/types_test.go b/config/types_test.go
new file mode 100644
index 0000000000000..8e35de6111c82
--- /dev/null
+++ b/config/types_test.go
@@ -0,0 +1,31 @@
+package config_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/influxdata/telegraf/config"
+	"github.com/influxdata/telegraf/plugins/processors/reverse_dns"
+	"github.com/stretchr/testify/require"
+)
+
+func TestConfigDuration(t *testing.T) {
+	c := config.NewConfig()
+	err := c.LoadConfigData([]byte(`
+[[processors.reverse_dns]]
+  cache_ttl = "3h"
+  lookup_timeout = "17s"
+  max_parallel_lookups = 13
+  ordered = true
+  [[processors.reverse_dns.lookup]]
+    field = "source_ip"
+    dest = "source_name"
+`))
+	require.NoError(t, err)
+	require.Len(t, c.Processors, 1)
+	p := c.Processors[0].Processor.(*reverse_dns.ReverseDNS)
+	require.EqualValues(t, p.CacheTTL, 3*time.Hour)
+	require.EqualValues(t, p.LookupTimeout, 17*time.Second)
+	require.Equal(t, p.MaxParallelLookups, 13)
+	require.Equal(t, p.Ordered, true)
+}
diff --git a/plugins/common/shim/config_test.go b/plugins/common/shim/config_test.go
index 1aee40df0f07a..be4ee4140feb5 100644
--- a/plugins/common/shim/config_test.go
+++ b/plugins/common/shim/config_test.go
@@ -3,8 +3,10 @@ package shim
 import (
 	"os"
 	"testing"
+	"time"
 
 	"github.com/influxdata/telegraf"
+	tgConfig "github.com/influxdata/telegraf/config"
 	"github.com/influxdata/telegraf/plugins/inputs"
 	"github.com/stretchr/testify/require"
 )
@@ -37,3 +39,34 @@ func TestDefaultImportedPluginsSelfRegisters(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, "test", cfg.Input.Description())
 }
+
+func TestLoadingSpecialTypes(t *testing.T) {
+	inputs.Add("test", func() telegraf.Input {
+		return &testDurationInput{}
+	})
+
+	c := "./testdata/special.conf"
+	conf, err := LoadConfig(&c)
+	require.NoError(t, err)
+
+	inp := conf.Input.(*testDurationInput)
+
+	require.EqualValues(t, 3*time.Second, inp.Duration)
+	require.EqualValues(t, 3*1000*1000, inp.Size)
+}
+
+type testDurationInput struct {
+	Duration tgConfig.Duration `toml:"duration"`
+	Size     tgConfig.Size     `toml:"size"`
+}
+
+func (i *testDurationInput) SampleConfig() string {
+	return ""
+}
+
+func (i *testDurationInput) Description() string {
+	return ""
+}
+func (i *testDurationInput) Gather(acc telegraf.Accumulator) error {
+	return nil
+}
diff --git a/plugins/common/shim/testdata/special.conf b/plugins/common/shim/testdata/special.conf
new file mode 100644
index 0000000000000..c324b638497c5
--- /dev/null
+++ b/plugins/common/shim/testdata/special.conf
@@ -0,0 +1,4 @@
+# testing custom field types
+[[inputs.test]]
+	duration = "3s"
+  size = "3MB"
\ No newline at end of file
diff --git a/plugins/inputs/vsphere/endpoint.go b/plugins/inputs/vsphere/endpoint.go
index 93d74e63f7a52..0a24efe6ef982 100644
--- a/plugins/inputs/vsphere/endpoint.go
+++ b/plugins/inputs/vsphere/endpoint.go
@@ -887,7 +887,7 @@ func (e *Endpoint) chunkify(ctx context.Context, res *resourceKind, now time.Tim
 			// Determine time of last successful collection
 			metricName := e.getMetricNameForId(metric.CounterId)
 			if metricName == "" {
-				e.log.Info("Unable to find metric name for id %d. Skipping!", metric.CounterId)
+				e.log.Infof("Unable to find metric name for id %d. Skipping!", metric.CounterId)
 				continue
 			}
 			start, ok := e.hwMarks.Get(object.ref.Value, metricName)