diff --git a/src/main/java/io/github/hectorvent/floci/services/cloudwatch/metrics/AlarmSnsNotifier.java b/src/main/java/io/github/hectorvent/floci/services/cloudwatch/metrics/AlarmSnsNotifier.java
index a3b9f35..41332ef 100644
--- a/src/main/java/io/github/hectorvent/floci/services/cloudwatch/metrics/AlarmSnsNotifier.java
+++ b/src/main/java/io/github/hectorvent/floci/services/cloudwatch/metrics/AlarmSnsNotifier.java
@@ -3,8 +3,6 @@ package io.github.hectorvent.floci.services.cloudwatch.metrics;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import io.github.hectorvent.floci.core.common.AwsArnUtils;
-import io.github.hectorvent.floci.core.common.AwsPartition;
-import io.github.hectorvent.floci.core.common.AwsPartitions;
 import io.github.hectorvent.floci.services.cloudwatch.metrics.model.MetricAlarm;
 import io.github.hectorvent.floci.services.sns.SnsService;
 import jakarta.enterprise.context.ApplicationScoped;
@@ -22,6 +20,38 @@ import java.util.Map;
 @ApplicationScoped
 public class AlarmSnsNotifier {
 
+    /** The names CloudWatch writes in the alarm message's Region field; other regions use their ID. */
+    private static final Map<String, String> REGION_NAMES = Map.ofEntries(
+            Map.entry("us-east-1", "US East (N. Virginia)"),
+            Map.entry("us-east-2", "US East (Ohio)"),
+            Map.entry("us-west-1", "US West (N. California)"),
+            Map.entry("us-west-2", "US West (Oregon)"),
+            Map.entry("ca-central-1", "Canada (Central)"),
+            Map.entry("ca-west-1", "Canada West (Calgary)"),
+            Map.entry("sa-east-1", "South America (Sao Paulo)"),
+            Map.entry("eu-west-1", "EU (Ireland)"),
+            Map.entry("eu-west-2", "EU (London)"),
+            Map.entry("eu-west-3", "EU (Paris)"),
+            Map.entry("eu-central-1", "EU (Frankfurt)"),
+            Map.entry("eu-central-2", "EU (Zurich)"),
+            Map.entry("eu-north-1", "EU (Stockholm)"),
+            Map.entry("eu-south-1", "EU (Milan)"),
+            Map.entry("eu-south-2", "EU (Spain)"),
+            Map.entry("me-south-1", "Middle East (Bahrain)"),
+            Map.entry("me-central-1", "Middle East (UAE)"),
+            Map.entry("il-central-1", "Israel (Tel Aviv)"),
+            Map.entry("af-south-1", "Africa (Cape Town)"),
+            Map.entry("ap-east-1", "Asia Pacific (Hong Kong)"),
+            Map.entry("ap-south-1", "Asia Pacific (Mumbai)"),
+            Map.entry("ap-south-2", "Asia Pacific (Hyderabad)"),
+            Map.entry("ap-northeast-1", "Asia Pacific (Tokyo)"),
+            Map.entry("ap-northeast-2", "Asia Pacific (Seoul)"),
+            Map.entry("ap-northeast-3", "Asia Pacific (Osaka)"),
+            Map.entry("ap-southeast-1", "Asia Pacific (Singapore)"),
+            Map.entry("ap-southeast-2", "Asia Pacific (Sydney)"),
+            Map.entry("ap-southeast-3", "Asia Pacific (Jakarta)"),
+            Map.entry("ap-southeast-4", "Asia Pacific (Melbourne)"));
+
     private static final Logger LOG = Logger.getLogger(AlarmSnsNotifier.class);
     private static final DateTimeFormatter TIMESTAMP_FORMAT = DateTimeFormatter
             .ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ", Locale.ROOT).withZone(ZoneOffset.UTC);
@@ -74,11 +104,7 @@ public class AlarmSnsNotifier {
         payload.put("NewStateValue", alarm.getStateValue());
         payload.put("NewStateReason", alarm.getStateReason());
         payload.put("StateChangeTime", timestamp(alarm.getStateUpdatedTimestamp()));
-        String regionName = AwsPartitions.forRegion(arn.region()).stream()
-                .flatMap(partition -> partition.regions().stream())
-                .filter(region -> region.id().equals(arn.region()))
-                .map(AwsPartition.Region::description).findFirst().orElse(arn.region());
-        payload.put("Region", regionName);
+        payload.put("Region", REGION_NAMES.getOrDefault(arn.region(), arn.region()));
         payload.put("AlarmArn", alarm.getAlarmArn());
         payload.put("OldStateValue", oldState);
         payload.put("OKActions", alarm.getOkActions());