diff --git a/CHANGELOG.md b/CHANGELOG.md
index 12f4cd3f..f068cedb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,16 @@
 CHANGELOG
 =========
 
+5.0.2 (unreleased)
+------------------
+
+* Fixed an issue where decoding `IpRiskResponse` from the IP Risk database would
+  fail when the `ip_risk` field was not present in the database record. The
+  `ipRisk` field now defaults to 0.0 when not present. A value of 0.0 indicates
+  that the risk score was not set in the database. In a future major release,
+  this field may be changed to a nullable `Double` to better distinguish between
+  "no data" and "zero risk". Reported by Fabrice Bacchella. GitHub #644.
+
 5.0.1 (2025-12-02)
 ------------------
 
diff --git a/src/main/java/com/maxmind/geoip2/model/IpRiskResponse.java b/src/main/java/com/maxmind/geoip2/model/IpRiskResponse.java
index 4795ae18..b137e4e2 100644
--- a/src/main/java/com/maxmind/geoip2/model/IpRiskResponse.java
+++ b/src/main/java/com/maxmind/geoip2/model/IpRiskResponse.java
@@ -28,8 +28,14 @@
  * @param isTorExitNode Whether the IP address is a Tor exit node.
  * @param network The network associated with the record. In particular, this is the largest
  *                network where all the fields besides IP address have the same value.
- * @param ipRisk The IP risk of a model.
+ * @param ipRisk The IP risk score for the IP address. A value of 0.0 indicates that the
+ *               risk score was not set in the database. This is a limitation of primitive
+ *               types in Java - the value cannot be null. In a future major version, this
+ *               field may be changed to a nullable {@code Double} to distinguish between
+ *               "no data" and "zero risk".
  */
+// TODO: In the next major version (6.0.0), consider changing ipRisk to Double
+// to allow null values, distinguishing "no data" from "zero risk".
 public record IpRiskResponse(
     @JsonProperty("ip_address")
     @MaxMindDbIpAddress
@@ -65,7 +71,7 @@ public record IpRiskResponse(
     Network network,
 
     @JsonProperty("ip_risk")
-    @MaxMindDbParameter(name = "ip_risk")
+    @MaxMindDbParameter(name = "ip_risk", useDefault = true)
     double ipRisk
 ) implements JsonSerializable {
 
diff --git a/src/test/java/com/maxmind/geoip2/DatabaseReaderTest.java b/src/test/java/com/maxmind/geoip2/DatabaseReaderTest.java
index b92e1a1c..21b1e6e6 100644
--- a/src/test/java/com/maxmind/geoip2/DatabaseReaderTest.java
+++ b/src/test/java/com/maxmind/geoip2/DatabaseReaderTest.java
@@ -19,6 +19,7 @@
 import com.maxmind.geoip2.model.CountryResponse;
 import com.maxmind.geoip2.model.DomainResponse;
 import com.maxmind.geoip2.model.EnterpriseResponse;
+import com.maxmind.geoip2.model.IpRiskResponse;
 import com.maxmind.geoip2.model.IspResponse;
 import java.io.File;
 import java.io.IOException;
@@ -427,6 +428,48 @@ public void testIsp() throws Exception {
         }
     }
 
+    @Test
+    public void testIpRisk() throws Exception {
+        try (DatabaseReader reader = new DatabaseReader.Builder(
+            this.getFile("GeoIP2-IP-Risk-Test.mmdb")).build()
+        ) {
+            InetAddress ipAddress = InetAddress.getByName("214.2.3.0");
+            IpRiskResponse response = reader.ipRisk(ipAddress);
+            assertEquals(25.0, response.ipRisk());
+            assertTrue(response.isAnonymous());
+            assertTrue(response.isAnonymousVpn());
+            assertFalse(response.isHostingProvider());
+            assertFalse(response.isPublicProxy());
+            assertFalse(response.isResidentialProxy());
+            assertFalse(response.isTorExitNode());
+            assertEquals(ipAddress.getHostAddress(), response.ipAddress().getHostAddress());
+            assertEquals("214.2.3.0/30", response.network().toString());
+
+            IpRiskResponse tryResponse = reader.tryIpRisk(ipAddress).get();
+            assertEquals(response.toJson(), tryResponse.toJson());
+        }
+    }
+
+    @Test
+    public void testIpRiskWithoutIpRiskField() throws Exception {
+        // Test that records without ip_risk field default to 0.0.
+        // A value of 0.0 indicates that the risk score was not set in the database.
+        try (DatabaseReader reader = new DatabaseReader.Builder(
+            this.getFile("GeoIP2-IP-Risk-Test.mmdb")).build()
+        ) {
+            InetAddress ipAddress = InetAddress.getByName("11.1.2.3");
+            IpRiskResponse response = reader.ipRisk(ipAddress);
+            assertEquals(0.0, response.ipRisk());
+            assertTrue(response.isAnonymous());
+            assertFalse(response.isAnonymousVpn());
+            assertFalse(response.isHostingProvider());
+            assertTrue(response.isPublicProxy());
+            assertFalse(response.isResidentialProxy());
+            assertFalse(response.isTorExitNode());
+            assertEquals(ipAddress.getHostAddress(), response.ipAddress().getHostAddress());
+        }
+    }
+
     private File getFile(String filename) throws URISyntaxException {
         URL resource = DatabaseReaderTest.class
             .getResource("/maxmind-db/test-data/" + filename);
diff --git a/src/test/resources/maxmind-db b/src/test/resources/maxmind-db
index f387805e..b6eb21df 160000
--- a/src/test/resources/maxmind-db
+++ b/src/test/resources/maxmind-db
@@ -1 +1 @@
-Subproject commit f387805e4af30036ec4245c9069ac1f2fdae4953
+Subproject commit b6eb21df882cc939d6b31bc05811a101f17fe148