diff --git a/src/main/java/com/google/devtools/build/lib/buildtool/BuildTool.java b/src/main/java/com/google/devtools/build/lib/buildtool/BuildTool.java
index 8a693ab..79913df 100644
--- a/src/main/java/com/google/devtools/build/lib/buildtool/BuildTool.java
+++ b/src/main/java/com/google/devtools/build/lib/buildtool/BuildTool.java
@@ -302,16 +302,17 @@
     } catch (InterruptedException e) {
       // We may have been interrupted by an error, or the user's interruption may have raced with
       // an error, so check to see if we should report that error code instead.
-      ExitCode environmentPendingExitCode = env.getPendingExitCode();
-      if (environmentPendingExitCode == null) {
+      AbruptExitException environmentPendingAbruptExitException = env.getPendingException();
+      if (environmentPendingAbruptExitException == null) {
         detailedExitCode = DetailedExitCode.justExitCode(ExitCode.INTERRUPTED);
         env.getReporter().handle(Event.error("build interrupted"));
         env.getEventBus().post(new BuildInterruptedEvent());
       } else {
         // Report the exception from the environment - the exception we're handling here is just an
         // interruption.
-        detailedExitCode = DetailedExitCode.justExitCode(environmentPendingExitCode);
-        reportExceptionError(env.getPendingException());
+        detailedExitCode =
+            DetailedExitCode.justExitCode(environmentPendingAbruptExitException.getExitCode());
+        reportExceptionError(environmentPendingAbruptExitException);
         result.setCatastrophe();
       }
     } catch (TargetParsingException | LoadingFailedException | ViewCreationFailedException e) {
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java b/src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java
index 50e6f9c..07a31ee 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java
@@ -54,6 +54,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.TreeMap;
 import java.util.TreeSet;
@@ -96,7 +97,14 @@
   private Path workingDirectory;
   private String workspaceName;
   private boolean haveSetupPackageCache = false;
-  private AtomicReference<AbruptExitException> pendingException = new AtomicReference<>();
+
+  // This AtomicReference is set to:
+  //   - null, if neither BlazeModuleEnvironment#exit nor #precompleteCommand have been called
+  //   - Optional.of(e), if BlazeModuleEnvironment#exit has been called with value e
+  //   - Optional.empty(), if #precompleteCommand was called before any call to
+  //     BlazeModuleEnvironment#exit
+  private final AtomicReference<Optional<AbruptExitException>> pendingException =
+      new AtomicReference<>();
 
   private final Object fileCacheLock = new Object();
 
@@ -117,7 +125,7 @@
     public void exit(AbruptExitException exception) {
       Preconditions.checkNotNull(exception);
       Preconditions.checkNotNull(exception.getExitCode());
-      if (pendingException.compareAndSet(null, exception)) {
+      if (pendingException.compareAndSet(null, Optional.of(exception))) {
         // There was no exception, so we're the first one to ask for an exit. Interrupt the command.
         commandThread.interrupt();
       }
@@ -523,7 +531,7 @@
   private ExitCode finalizeExitCode() {
     // Set the pending exception so that further calls to exit(AbruptExitException) don't lead to
     // unwanted thread interrupts.
-    if (pendingException.compareAndSet(null, new AbruptExitException("", ExitCode.RESERVED))) {
+    if (pendingException.compareAndSet(null, Optional.empty())) {
       return null;
     }
     if (Thread.currentThread() == commandThread) {
@@ -545,11 +553,9 @@
     return finalizeExitCode();
   }
 
-  /**
-   * Returns the current exit code requested by modules, or null if no exit has been requested.
-   */
+  /** Returns the current exit code requested by modules, or null if no exit has been requested. */
   @Nullable
-  public ExitCode getPendingExitCode() {
+  private ExitCode getPendingExitCode() {
     AbruptExitException exception = getPendingException();
     return exception == null ? null : exception.getExitCode();
   }
@@ -559,8 +565,10 @@
    *
    * <p>Prefer getPendingExitCode or throwPendingException where appropriate.
    */
+  @Nullable
   public AbruptExitException getPendingException() {
-    return pendingException.get();
+    Optional<AbruptExitException> abruptExitExceptionMaybe = pendingException.get();
+    return abruptExitExceptionMaybe == null ? null : abruptExitExceptionMaybe.orElse(null);
   }
 
   /**