diff --git a/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java b/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java
index e48f545c5..7fa27135e 100644
--- a/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java
+++ b/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java
@@ -35,6 +35,9 @@ static void writeTimestamp(Writer writer, long timestampMs) throws IOException {
   }
 
   static void writeEscapedLabelValue(Writer writer, String s) throws IOException {
+    if (s == null) {
+      return;
+    }
     for (int i = 0; i < s.length(); i++) {
       char c = s.charAt(i);
       switch (c) {