diff --git a/changelog/@unreleased/pr-2427.v2.yml b/changelog/@unreleased/pr-2427.v2.yml
new file mode 100644
index 000000000..fbee64d40
--- /dev/null
+++ b/changelog/@unreleased/pr-2427.v2.yml
@@ -0,0 +1,5 @@
+type: fix
+fix:
+  description: Fix ConcurrentModificationExceptions thrown from BaselineNullAway
+  links:
+  - https://github.com/palantir/gradle-baseline/pull/2427
diff --git a/gradle-baseline-java/src/main/groovy/com/palantir/baseline/plugins/BaselineNullAway.java b/gradle-baseline-java/src/main/groovy/com/palantir/baseline/plugins/BaselineNullAway.java
index 6e21da8db..0db9611cb 100644
--- a/gradle-baseline-java/src/main/groovy/com/palantir/baseline/plugins/BaselineNullAway.java
+++ b/gradle-baseline-java/src/main/groovy/com/palantir/baseline/plugins/BaselineNullAway.java
@@ -134,7 +134,7 @@ public void execute(Configuration _files) {
 
     private static boolean anyProjectUsesJava15(Project proj) {
         return proj.getAllprojects().stream()
-                .anyMatch(project -> project.getTasks().withType(JavaCompile.class).stream()
+                .anyMatch(project -> ImmutableList.copyOf(project.getTasks().withType(JavaCompile.class)).stream()
                         .anyMatch(comp -> {
                             JavaVersion javaVersion = JavaVersion.toVersion(comp.getTargetCompatibility());
                             return javaVersion == JavaVersion.VERSION_15;