diff --git a/DESCRIPTION b/DESCRIPTION
index 195a962..2d90d16 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,8 +1,8 @@
 Package: RNAmodR
 Type: Package
 Title: Detection of post-transcriptional modifications in high throughput sequencing data
-Version: 1.7.1
-Date: 2021-07-27
+Version: 1.7.2
+Date: 2021-08-25
 Authors@R: c(person("Felix G.M.", 
                     "Ernst", 
                     email = "felix.gm.ernst@outlook.com", 
diff --git a/R/SequenceData-pileup.R b/R/SequenceData-pileup.R
index 4d11a37..3fdba50 100644
--- a/R/SequenceData-pileup.R
+++ b/R/SequenceData-pileup.R
@@ -143,8 +143,10 @@ setSequenceDataCoercions("Pileup")
   strands_u <- .get_strand_u_GRangesList(grl)
   pileup <- pileup[pileup[,"strand"] == strands_u]
   # sort rev on minus strand
-  pileup[strands_u == "-"] <- 
-    pileup[strands_u == "-"][order(pileup[strands_u == "-","pos"],decreasing = FALSE)]
+  f <- strands_u == "-"
+  if(any(f)){
+    pileup[f] <- pileup[f][order(pileup[f,"pos"],decreasing = FALSE)]
+  }
   pileup <- pileup[,c("-","G","A","T","C")]
   pileup
 }