diff --git a/R/methods-AlignmentPairsList-class.R b/R/methods-AlignmentPairsList-class.R
index 4417382..cb5fc49 100644
--- a/R/methods-AlignmentPairsList-class.R
+++ b/R/methods-AlignmentPairsList-class.R
@@ -87,8 +87,8 @@ setMethod("geneBodyCoverage", signature = c("AlignmentPairsList"),
                                       BPPARAM=bpparam)
     }
     x <- bind_rows(lapply(gbc, data.frame), .id="id")
-    if (!is.null(names(apl)))
-        x[["id"]] <- factor(x[["id"]], levels=names(apl))
+    if (!is.null(names(obj)))
+        x[["id"]] <- factor(x[["id"]], levels=names(obj))
     x
 })