diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaImport.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaImport.java
index cfbb4051adb20d..bfcc7b186fa6b1 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaImport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaImport.java
@@ -106,7 +106,7 @@ public ConfiguredTarget create(RuleContext ruleContext)
     filesBuilder.addAll(jars);
 
     ImmutableBiMap<Artifact, Artifact> compilationToRuntimeJarMap =
-        compilationToRuntimeJarMapBuilder.build();
+        compilationToRuntimeJarMapBuilder.buildOrThrow();
 
     NestedSet<Artifact> filesToBuild = filesBuilder.build();