diff --git a/prometheus-metrics-model/src/main/java/io/prometheus/metrics/model/snapshots/PrometheusNaming.java b/prometheus-metrics-model/src/main/java/io/prometheus/metrics/model/snapshots/PrometheusNaming.java
index 06e004398..21c162632 100644
--- a/prometheus-metrics-model/src/main/java/io/prometheus/metrics/model/snapshots/PrometheusNaming.java
+++ b/prometheus-metrics-model/src/main/java/io/prometheus/metrics/model/snapshots/PrometheusNaming.java
@@ -157,7 +157,7 @@ public static String sanitizeMetricName(String metricName) {
      * as a suffix if the unit is not {@code null}.
      */
     public static String sanitizeMetricName(String metricName, Unit unit) {
-        String result = sanitizeLabelName(metricName);
+        String result = sanitizeMetricName(metricName);
         if (unit != null) {
             if (!result.endsWith("_" + unit) && !result.endsWith("." + unit)) {
                 result += "_" + unit;
@@ -224,8 +224,7 @@ private static String replaceIllegalCharsInMetricName(String name) {
         char[] sanitized = new char[length];
         for (int i = 0; i < length; i++) {
             char ch = name.charAt(i);
-            if (ch == ':' ||
-                    ch == '.' ||
+            if (ch == '.' ||
                     (ch >= 'a' && ch <= 'z') ||
                     (ch >= 'A' && ch <= 'Z') ||
                     (i > 0 && ch >= '0' && ch <= '9')) {
diff --git a/prometheus-metrics-model/src/test/java/io/prometheus/metrics/model/snapshots/PrometheusNamingTest.java b/prometheus-metrics-model/src/test/java/io/prometheus/metrics/model/snapshots/PrometheusNamingTest.java
index 3a7788743..9631f9df3 100644
--- a/prometheus-metrics-model/src/test/java/io/prometheus/metrics/model/snapshots/PrometheusNamingTest.java
+++ b/prometheus-metrics-model/src/test/java/io/prometheus/metrics/model/snapshots/PrometheusNamingTest.java
@@ -10,7 +10,7 @@ public class PrometheusNamingTest {
     @Test
     public void testSanitizeMetricName() {
         Assert.assertEquals("_abc_def", prometheusName(sanitizeMetricName("0abc.def")));
-        Assert.assertEquals("___ab_:c0", prometheusName(sanitizeMetricName("___ab.:c0")));
+        Assert.assertEquals("___ab__c0", prometheusName(sanitizeMetricName("___ab.:c0")));
         Assert.assertEquals("my_prefix_my_metric", sanitizeMetricName("my_prefix/my_metric"));
         Assert.assertEquals("my_counter", prometheusName(sanitizeMetricName("my_counter_total")));
         Assert.assertEquals("jvm", sanitizeMetricName("jvm.info"));
@@ -21,6 +21,20 @@ public void testSanitizeMetricName() {
         Assert.assertEquals("total", sanitizeMetricName("total"));
     }
 
+    @Test
+    public void testSanitizeMetricNameWithUnit() {
+        Assert.assertEquals("_abc_def_" + Unit.RATIO, prometheusName(sanitizeMetricName("0abc.def", Unit.RATIO)));
+        Assert.assertEquals("___ab__c0_" + Unit.RATIO, prometheusName(sanitizeMetricName("___ab.:c0", Unit.RATIO)));
+        Assert.assertEquals("my_prefix_my_metric_" + Unit.RATIO, sanitizeMetricName("my_prefix/my_metric", Unit.RATIO));
+        Assert.assertEquals("my_counter_" + Unit.RATIO, prometheusName(sanitizeMetricName("my_counter_total", Unit.RATIO)));
+        Assert.assertEquals("jvm_" + Unit.RATIO, sanitizeMetricName("jvm.info", Unit.RATIO));
+        Assert.assertEquals("jvm_" + Unit.RATIO, sanitizeMetricName("jvm_info", Unit.RATIO));
+        Assert.assertEquals("jvm_" + Unit.RATIO, sanitizeMetricName("jvm.info", Unit.RATIO));
+        Assert.assertEquals("a.b_" + Unit.RATIO, sanitizeMetricName("a.b", Unit.RATIO));
+        Assert.assertEquals("total_" + Unit.RATIO, sanitizeMetricName("_total", Unit.RATIO));
+        Assert.assertEquals("total_" + Unit.RATIO, sanitizeMetricName("total", Unit.RATIO));
+    }
+
     @Test
     public void testSanitizeLabelName() {
         Assert.assertEquals("_abc_def", prometheusName(sanitizeLabelName("0abc.def")));