diff --git a/README.md b/README.md
index d2e9829..6e1f505 100644
--- a/README.md
+++ b/README.md
@@ -9,10 +9,13 @@ Data is read from stdin over a unix pipe, eliminating the need for any intermidi
PretextMap comes with no imposed pipeline for processing data. Process your alignments however you want before feeding to PretextMap.
# Usage
-Pipe SAM or pairs formatted read pairs to PretextMap e.g. samtools view -h file.bam | PretextMap, zcat file.paris.gz | PretextMap
+Pipe SAM or pairs formatted read pairs to PretextMap e.g.:
+samtools view -h file.bam | PretextMap
+zcat file.paris.gz | PretextMap
+
Important: A SAM header with contig info must be present for SAM format (-h option for samtools).
+
Or pipe directly from an aligner e.g. bwa mem ... | PretextMap
-Note:
# Options
-o specifies an output file (required)