diff --git a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfiguration.java b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfiguration.java
index 19cb762a3c..7e267f8f74 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfiguration.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfiguration.java
@@ -146,11 +146,11 @@ public class CassandraAutoConfiguration {
 	}
 
 	private void mapPoolingOptions(CassandraProperties properties, CassandraDriverOptions options) {
-		PropertyMapper map = PropertyMapper.get();
+		PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
 		CassandraProperties.Pool poolProperties = properties.getPool();
-		map.from(poolProperties::getIdleTimeout).whenNonNull().asInt(Duration::getSeconds)
+		map.from(poolProperties::getIdleTimeout).asInt(Duration::toMillis)
 				.to((idleTimeout) -> options.add(DefaultDriverOption.HEARTBEAT_TIMEOUT, idleTimeout));
-		map.from(poolProperties::getHeartbeatInterval).whenNonNull().asInt(Duration::getSeconds)
+		map.from(poolProperties::getHeartbeatInterval).asInt(Duration::toMillis)
 				.to((heartBeatInterval) -> options.add(DefaultDriverOption.HEARTBEAT_INTERVAL, heartBeatInterval));
 	}
 
diff --git a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraProperties.java b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraProperties.java
index f4f2ce0859..df6a983746 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraProperties.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraProperties.java
@@ -17,7 +17,6 @@
 package org.springframework.boot.autoconfigure.cassandra;
 
 import java.time.Duration;
-import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -26,7 +25,6 @@ import com.datastax.oss.driver.api.core.DefaultConsistencyLevel;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.DeprecatedConfigurationProperty;
-import org.springframework.boot.convert.DurationUnit;
 
 /**
  * Configuration properties for Cassandra.
@@ -360,18 +358,14 @@ public class CassandraProperties {
 	public static class Pool {
 
 		/**
-		 * Idle timeout before an idle connection is removed. If a duration suffix is not
-		 * specified, seconds will be used.
+		 * Idle timeout before an idle connection is removed.
 		 */
-		@DurationUnit(ChronoUnit.SECONDS)
 		private Duration idleTimeout = Duration.ofSeconds(120);
 
 		/**
 		 * Heartbeat interval after which a message is sent on an idle connection to make
-		 * sure it's still alive. If a duration suffix is not specified, seconds will be
-		 * used.
+		 * sure it's still alive.
 		 */
-		@DurationUnit(ChronoUnit.SECONDS)
 		private Duration heartbeatInterval = Duration.ofSeconds(30);
 
 		public Duration getIdleTimeout() {