diff --git a/bridge.go b/bridge.go
index bb86487..89447d0 100644
--- a/bridge.go
+++ b/bridge.go
@@ -10,12 +10,17 @@ import (
 	"fmt"
 	"log"
 	"net"
+	"regexp"
 	"strconv"
 	"strings"
 
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+var (
+	illegalCharsRE = regexp.MustCompile(`[^a-zA-Z0-9_]`)
+)
+
 type CounterContainer struct {
 	Elements map[string]prometheus.Counter
 }
@@ -121,10 +126,13 @@ type Bridge struct {
 }
 
 func escapeMetricName(metricName string) string {
-	// TODO: evaluate what kind of escaping we really want.
-	metricName = strings.Replace(metricName, "_", "__", -1)
-	metricName = strings.Replace(metricName, "-", "__", -1)
-	metricName = strings.Replace(metricName, ".", "_", -1)
+	// If a metric starts with a digit, prepend an underscore.
+	if metricName[0] >= '0' && metricName[0] <= '9' {
+		metricName = "_" + metricName
+	}
+
+	// Replace all illegal metric chars with underscores.
+	metricName = illegalCharsRE.ReplaceAllString(metricName, "_")
 	return metricName
 }
 
diff --git a/mapper.go b/mapper.go
index 7cd374c..12162b2 100644
--- a/mapper.go
+++ b/mapper.go
@@ -20,6 +20,7 @@ var (
 	identifierRE = `[a-zA-Z_][a-zA-Z0-9_]+`
 	metricLineRE = regexp.MustCompile(`^(\*\.|` + identifierRE + `\.)+(\*|` + identifierRE + `)$`)
 	labelLineRE  = regexp.MustCompile(`^(` + identifierRE + `)\s*=\s*"(.*)"$`)
+	metricNameRE = regexp.MustCompile(`^` + identifierRE + `$`)
 )
 
 type metricMapping struct {
@@ -85,7 +86,11 @@ func (m *metricMapper) initFromString(fileContents string) error {
 			if len(matches) != 3 {
 				return fmt.Errorf("Line %d: expected label mapping line, got: %s", i, line)
 			}
-			currentMapping.labels[matches[1]] = matches[2]
+			label, value := matches[1], matches[2]
+			if label == "name" && !metricNameRE.MatchString(value) {
+				return fmt.Errorf("Line %d: metric name '%s' doesn't match regex '%s'", i, value, metricNameRE)
+			}
+			currentMapping.labels[label] = value
 		default:
 			panic("illegal state")
 		}
diff --git a/mapper_test.go b/mapper_test.go
index 87ca71a..6b9ccb2 100644
--- a/mapper_test.go
+++ b/mapper_test.go
@@ -69,6 +69,14 @@ func TestMetricMapper(t *testing.T) {
 			`,
 			configBad: true,
 		},
+		// Config with bad metric name.
+		{
+			config: `
+				test.*.*
+				name="0foo"
+			`,
+			configBad: true,
+		},
 	}
 
 	mapper := metricMapper{}