diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/FileSystemValueCheckerInferringAncestors.java b/src/main/java/com/google/devtools/build/lib/skyframe/FileSystemValueCheckerInferringAncestors.java
index fd905a35929919..6b2f276dfabc96 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/FileSystemValueCheckerInferringAncestors.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/FileSystemValueCheckerInferringAncestors.java
@@ -165,6 +165,10 @@ private ImmutableDiff processEntries(int nThreads)
     ImmutableList<Future<?>> futures =
         nodeStates.entrySet().stream()
             .filter(e -> e.getValue().childrenToProcess.get() == 0)
+            // Materialize all leaves before scheduling them -- otherwise, we could race with the
+            // processing code which decrements childrenToProcess.
+            .collect(toImmutableList())
+            .stream()
             .map(
                 e ->
                     executor.submit(