diff --git a/java/droiddoc.go b/java/droiddoc.go
index 62a6661..4b4a245 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -1308,13 +1308,10 @@
 		d.annotationsZip = android.PathForModuleOut(ctx, ctx.ModuleName()+"_annotations.zip")
 		cmd.FlagWithOutput("--extract-annotations ", d.annotationsZip)
 
-		if len(d.properties.Merge_annotations_dirs) == 0 {
-			ctx.PropertyErrorf("merge_annotations_dirs",
-				"has to be non-empty if annotations was enabled!")
+		if len(d.properties.Merge_annotations_dirs) != 0 {
+			d.mergeAnnoDirFlags(ctx, cmd)
 		}
 
-		d.mergeAnnoDirFlags(ctx, cmd)
-
 		// TODO(tnorbye): find owners to fix these warnings when annotation was enabled.
 		cmd.FlagWithArg("--hide ", "HiddenTypedefConstant").
 			FlagWithArg("--hide ", "SuperfluousPrefix").