diff --git a/pkg/services/ngalert/state/cache.go b/pkg/services/ngalert/state/cache.go
index 360ba0aa490..a1e9e437b66 100644
--- a/pkg/services/ngalert/state/cache.go
+++ b/pkg/services/ngalert/state/cache.go
@@ -3,6 +3,7 @@ package state
 import (
 	"bytes"
 	"fmt"
+	"math"
 	"strconv"
 	"strings"
 	"sync"
@@ -110,16 +111,13 @@ func (c *cache) expandRuleLabelsAndAnnotations(alertRule *ngModels.AlertRule, la
 // and labels template.
 type templateCaptureValue struct {
 	Labels map[string]string
-	Value  *float64
+	Value  float64
 }
 
 // String implements the Stringer interface to print the value of each RefID
 // in the template via {{ $values.A }} rather than {{ $values.A.Value }}.
 func (v templateCaptureValue) String() string {
-	if v.Value != nil {
-		return strconv.FormatFloat(*v.Value, 'f', -1, 64)
-	}
-	return "null"
+	return strconv.FormatFloat(v.Value, 'f', -1, 64)
 }
 
 func expandTemplate(name, text string, labels map[string]string, alertInstance eval.Result) (result string, resultErr error) {
@@ -148,23 +146,31 @@ func expandTemplate(name, text string, labels map[string]string, alertInstance e
 		Value  string
 	}{
 		Labels: labels,
-		Values: func() map[string]templateCaptureValue {
-			m := make(map[string]templateCaptureValue)
-			for k, v := range alertInstance.Values {
-				m[k] = templateCaptureValue{
-					Labels: v.Labels,
-					Value:  v.Value,
-				}
-			}
-			return m
-		}(),
-		Value: alertInstance.EvaluationString,
+		Values: newTemplateCaptureValues(alertInstance.Values),
+		Value:  alertInstance.EvaluationString,
 	}); err != nil {
 		return "", fmt.Errorf("error executing template %v: %s", name, err.Error())
 	}
 	return buffer.String(), nil
 }
 
+func newTemplateCaptureValues(values map[string]eval.NumberValueCapture) map[string]templateCaptureValue {
+	m := make(map[string]templateCaptureValue)
+	for k, v := range values {
+		var f float64
+		if v.Value != nil {
+			f = *v.Value
+		} else {
+			f = math.NaN()
+		}
+		m[k] = templateCaptureValue{
+			Labels: v.Labels,
+			Value:  f,
+		}
+	}
+	return m
+}
+
 func (c *cache) set(entry *State) {
 	c.mtxStates.Lock()
 	defer c.mtxStates.Unlock()
diff --git a/pkg/services/ngalert/state/cache_test.go b/pkg/services/ngalert/state/cache_test.go
index 946a2c6352b..9f553105ced 100644
--- a/pkg/services/ngalert/state/cache_test.go
+++ b/pkg/services/ngalert/state/cache_test.go
@@ -17,16 +17,16 @@ func TestTemplateCaptureValueStringer(t *testing.T) {
 		value    templateCaptureValue
 		expected string
 	}{{
-		name:     "nil value returns null",
-		value:    templateCaptureValue{Value: nil},
-		expected: "null",
+		name:     "0 is returned as integer value",
+		value:    templateCaptureValue{Value: 0},
+		expected: "0",
 	}, {
 		name:     "1.0 is returned as integer value",
-		value:    templateCaptureValue{Value: ptr.Float64(1.0)},
+		value:    templateCaptureValue{Value: 1.0},
 		expected: "1",
 	}, {
 		name:     "1.1 is returned as decimal value",
-		value:    templateCaptureValue{Value: ptr.Float64(1.1)},
+		value:    templateCaptureValue{Value: 1.1},
 		expected: "1.1",
 	}}
 
@@ -46,12 +46,12 @@ func TestExpandTemplate(t *testing.T) {
 		expected      string
 		expectedError error
 	}{{
-		name:     "instance labels are expanded into $labels",
+		name:     "labels are expanded into $labels",
 		text:     "{{ $labels.instance }} is down",
 		labels:   data.Labels{"instance": "foo"},
 		expected: "foo is down",
 	}, {
-		name:          "missing instance label returns error",
+		name:          "missing label in $labels returns error",
 		text:          "{{ $labels.instance }} is down",
 		labels:        data.Labels{},
 		expectedError: errors.New("error executing template __alert_test: template: __alert_test:1:86: executing \"__alert_test\" at <$labels.instance>: map has no entry for key \"instance\""),
@@ -63,11 +63,24 @@ func TestExpandTemplate(t *testing.T) {
 				"A": {
 					Var:    "A",
 					Labels: data.Labels{"instance": "foo"},
-					Value:  ptr.Float64(10),
+					Value:  ptr.Float64(1),
 				},
 			},
 		},
-		expected: "foo has value 10",
+		expected: "foo has value 1",
+	}, {
+		name: "values can be passed to template functions such as printf",
+		text: "{{ $values.A.Labels.instance }} has value {{ $values.A.Value | printf \"%.1f\" }}",
+		alertInstance: eval.Result{
+			Values: map[string]eval.NumberValueCapture{
+				"A": {
+					Var:    "A",
+					Labels: data.Labels{"instance": "foo"},
+					Value:  ptr.Float64(1.1),
+				},
+			},
+		},
+		expected: "foo has value 1.1",
 	}, {
 		name: "missing label in $values returns error",
 		text: "{{ $values.A.Labels.instance }} has value {{ $values.A }}",
@@ -76,13 +89,26 @@ func TestExpandTemplate(t *testing.T) {
 				"A": {
 					Var:    "A",
 					Labels: data.Labels{},
-					Value:  ptr.Float64(10),
+					Value:  ptr.Float64(1),
 				},
 			},
 		},
 		expectedError: errors.New("error executing template __alert_test: template: __alert_test:1:86: executing \"__alert_test\" at <$values.A.Labels.instance>: map has no entry for key \"instance\""),
 	}, {
-		name: "value string is expanded into $value",
+		name: "missing value in $values is returned as NaN",
+		text: "{{ $values.A.Labels.instance }} has value {{ $values.A }}",
+		alertInstance: eval.Result{
+			Values: map[string]eval.NumberValueCapture{
+				"A": {
+					Var:    "A",
+					Labels: data.Labels{"instance": "foo"},
+					Value:  nil,
+				},
+			},
+		},
+		expected: "foo has value NaN",
+	}, {
+		name: "assert value string is expanded into $value",
 		text: "{{ $value }}",
 		alertInstance: eval.Result{
 			EvaluationString: "[ var='A' labels={instance=foo} value=10 ]",