diff --git a/ch4/pom.xml b/ch4/pom.xml
index 11a5722..b523f98 100644
--- a/ch4/pom.xml
+++ b/ch4/pom.xml
@@ -13,7 +13,7 @@
 		<slf4j.version>1.6.6</slf4j.version>
 		<log4j.version>1.2.17</log4j.version>
 		<mockito.version>1.9.5-rc1</mockito.version>
-		<solr.version>4.10.3</solr.version>
+		<solr.version>9.8.0</solr.version>
 	</properties>
 	<licenses>
 		<license>