diff --git a/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/TransactionManagerCustomizers.java b/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/TransactionManagerCustomizers.java
index fb4073f77b8..f16be0cb8ba 100644
--- a/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/TransactionManagerCustomizers.java
+++ b/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/TransactionManagerCustomizers.java
@@ -21,6 +21,8 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.util.LambdaSafe;
 import org.springframework.transaction.TransactionManager;
 
@@ -56,7 +58,8 @@ public final class TransactionManagerCustomizers {
 	 * @param customizers the customizers
 	 * @return the new instance
 	 */
-	public static TransactionManagerCustomizers of(Collection<? extends TransactionManagerCustomizer<?>> customizers) {
+	public static TransactionManagerCustomizers of(
+			@Nullable Collection<? extends TransactionManagerCustomizer<?>> customizers) {
 		return new TransactionManagerCustomizers(
 				(customizers != null) ? new ArrayList<>(customizers) : Collections.emptyList());
 	}
diff --git a/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/TransactionProperties.java b/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/TransactionProperties.java
index f25b45baf54..7470fd5f450 100644
--- a/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/TransactionProperties.java
+++ b/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/TransactionProperties.java
@@ -19,6 +19,8 @@ package org.springframework.boot.transaction.autoconfigure;
 import java.time.Duration;
 import java.time.temporal.ChronoUnit;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.convert.DurationUnit;
 import org.springframework.transaction.support.AbstractPlatformTransactionManager;
@@ -39,26 +41,26 @@ public class TransactionProperties implements TransactionManagerCustomizer<Abstr
 	 * used.
 	 */
 	@DurationUnit(ChronoUnit.SECONDS)
-	private Duration defaultTimeout;
+	private @Nullable Duration defaultTimeout;
 
 	/**
 	 * Whether to roll back on commit failures.
 	 */
-	private Boolean rollbackOnCommitFailure;
+	private @Nullable Boolean rollbackOnCommitFailure;
 
-	public Duration getDefaultTimeout() {
+	public @Nullable Duration getDefaultTimeout() {
 		return this.defaultTimeout;
 	}
 
-	public void setDefaultTimeout(Duration defaultTimeout) {
+	public void setDefaultTimeout(@Nullable Duration defaultTimeout) {
 		this.defaultTimeout = defaultTimeout;
 	}
 
-	public Boolean getRollbackOnCommitFailure() {
+	public @Nullable Boolean getRollbackOnCommitFailure() {
 		return this.rollbackOnCommitFailure;
 	}
 
-	public void setRollbackOnCommitFailure(Boolean rollbackOnCommitFailure) {
+	public void setRollbackOnCommitFailure(@Nullable Boolean rollbackOnCommitFailure) {
 		this.rollbackOnCommitFailure = rollbackOnCommitFailure;
 	}
 
diff --git a/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/package-info.java b/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/package-info.java
index 039d1b392b2..4aedf8fc6fa 100644
--- a/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/package-info.java
+++ b/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/autoconfigure/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for transaction support.
  */
+@NullMarked
 package org.springframework.boot.transaction.autoconfigure;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/jta/autoconfigure/package-info.java b/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/jta/autoconfigure/package-info.java
index 268ff7f8ea1..c0432b15b20 100644
--- a/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/jta/autoconfigure/package-info.java
+++ b/module/spring-boot-tx/src/main/java/org/springframework/boot/transaction/jta/autoconfigure/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for JTA.
  */
+@NullMarked
 package org.springframework.boot.transaction.jta.autoconfigure;
+
+import org.jspecify.annotations.NullMarked;