diff --git a/java/sdk_library.go b/java/sdk_library.go
index d7f53ec..f2d0c59 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -2160,6 +2160,10 @@
 
 		// Save away the `deapexer` module on which this depends, if any.
 		if tag == android.DeapexerTag {
+			if deapexerModule != nil {
+				ctx.ModuleErrorf("Ambiguous duplicate deapexer module dependencies %q and %q",
+					deapexerModule.Name(), to.Name())
+			}
 			deapexerModule = to
 		}
 	})