diff --git a/README.md b/README.md
index f107186..676f830 100644
--- a/README.md
+++ b/README.md
@@ -16,4 +16,4 @@ The code requires the `biopython` and `matplotlib` modules:
 
 From the terminal use the following command to generate the read quality diagnostic plot:
 
-`python qcheck.py data/SRR622461_2.fastq data/SRR622461_2.fastq`
+`python qcheck.py data/SRR622461_1.fastq data/SRR622461_2.fastq`
diff --git a/qcheck.py b/qcheck.py
index fb9fb42..a41c75b 100644
--- a/qcheck.py
+++ b/qcheck.py
@@ -16,7 +16,7 @@
 # define plot function
 def myPlotFunc(fastq):
 	for i,rec in enumerate(SeqIO.parse(fastq,"fastq")):
-		if i >= 50:
+		if i >= 60:
 			break
 		plt.plot(rec.letter_annotations["phred_quality"])
 	plt.ylim(0,45)