diff --git a/src/OpenTelemetry.Exporter.Prometheus/Implementation/PrometheusSerializerExt.cs b/src/OpenTelemetry.Exporter.Prometheus/Implementation/PrometheusSerializerExt.cs
index dc98b92221c..805a51a2488 100644
--- a/src/OpenTelemetry.Exporter.Prometheus/Implementation/PrometheusSerializerExt.cs
+++ b/src/OpenTelemetry.Exporter.Prometheus/Implementation/PrometheusSerializerExt.cs
@@ -52,18 +52,13 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric)
                     {
                         buffer[cursor++] = unchecked((byte)'{');
 
-                        int i = 0;
                         foreach (var tag in tags)
                         {
-                            if (i++ > 0)
-                            {
-                                buffer[cursor++] = unchecked((byte)',');
-                            }
-
                             cursor = WriteLabel(buffer, cursor, tag.Key, tag.Value);
+                            buffer[cursor++] = unchecked((byte)',');
                         }
 
-                        buffer[cursor++] = unchecked((byte)'}');
+                        buffer[cursor - 1] = unchecked((byte)'}'); // Note: We write the '}' over the last written comma, which is extra.
                     }
 
                     buffer[cursor++] = unchecked((byte)' ');
@@ -151,18 +146,13 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric)
                     {
                         buffer[cursor++] = unchecked((byte)'{');
 
-                        int i = 0;
                         foreach (var tag in tags)
                         {
-                            if (i++ > 0)
-                            {
-                                buffer[cursor++] = unchecked((byte)',');
-                            }
-
                             cursor = WriteLabel(buffer, cursor, tag.Key, tag.Value);
+                            buffer[cursor++] = unchecked((byte)',');
                         }
 
-                        buffer[cursor++] = unchecked((byte)'}');
+                        buffer[cursor - 1] = unchecked((byte)'}'); // Note: We write the '}' over the last written comma, which is extra.
                     }
 
                     buffer[cursor++] = unchecked((byte)' ');
@@ -182,18 +172,13 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric)
                     {
                         buffer[cursor++] = unchecked((byte)'{');
 
-                        int i = 0;
                         foreach (var tag in tags)
                         {
-                            if (i++ > 0)
-                            {
-                                buffer[cursor++] = unchecked((byte)',');
-                            }
-
                             cursor = WriteLabel(buffer, cursor, tag.Key, tag.Value);
+                            buffer[cursor++] = unchecked((byte)',');
                         }
 
-                        buffer[cursor++] = unchecked((byte)'}');
+                        buffer[cursor - 1] = unchecked((byte)'}'); // Note: We write the '}' over the last written comma, which is extra.
                     }
 
                     buffer[cursor++] = unchecked((byte)' ');
diff --git a/src/OpenTelemetry.Exporter.Prometheus/PrometheusExporterOptions.cs b/src/OpenTelemetry.Exporter.Prometheus/PrometheusExporterOptions.cs
index cea95b37c04..e42fcb89bc3 100644
--- a/src/OpenTelemetry.Exporter.Prometheus/PrometheusExporterOptions.cs
+++ b/src/OpenTelemetry.Exporter.Prometheus/PrometheusExporterOptions.cs
@@ -16,6 +16,7 @@
 
 using System;
 using System.Collections.Generic;
+using OpenTelemetry.Internal;
 
 namespace OpenTelemetry.Exporter
 {
@@ -65,10 +66,7 @@ public int ScrapeResponseCacheDurationMilliseconds
             get => this.scrapeResponseCacheDurationMilliseconds;
             set
             {
-                if (value < 0)
-                {
-                    throw new ArgumentOutOfRangeException(nameof(value), "Value should be greater than or equal to zero.");
-                }
+                Guard.Range(value, nameof(value), min: 0);
 
                 this.scrapeResponseCacheDurationMilliseconds = value;
             }