diff --git a/spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfo.java b/spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfo.java
index f48226e5d843..4728caf87dc1 100644
--- a/spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfo.java
+++ b/spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfo.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -108,7 +108,7 @@ public void properties(Action<BuildInfoProperties> action) {
 
 	private Map<String, String> coerceToStringValues(Map<String, Object> input) {
 		Map<String, String> output = new HashMap<>();
-		input.forEach((key, value) -> output.put(key, value.toString()));
+		input.forEach((key, value) -> output.put(key, (value != null) ? value.toString() : null));
 		return output;
 	}
 
diff --git a/spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoTests.java b/spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoTests.java
index 441ebd4d2459..e1c86f4ab761 100644
--- a/spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoTests.java
+++ b/spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,6 +33,7 @@
 import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 /**
  * Tests for {@link BuildInfo}.
@@ -186,6 +187,14 @@ void additionalPropertiesAreReflectedInProperties() {
 		assertThat(buildInfoProperties(task)).containsEntry("build.b", "bravo");
 	}
 
+	@Test
+	void nullAdditionalPropertyProducesInformativeFailure() {
+		BuildInfo task = createTask(createProject("test"));
+		task.getProperties().getAdditional().put("a", null);
+		assertThatThrownBy(() -> buildInfoProperties(task))
+				.hasMessage("Additional property 'a' is illegal as its value is null");
+	}
+
 	private Project createProject(String projectName) {
 		File projectDir = new File(this.temp, projectName);
 		Project project = GradleProjectBuilder.builder().withProjectDir(projectDir).withName(projectName).build();