diff --git a/README.md b/README.md
index e7ee075..15a2db3 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ cd ..
 
 ./deSPI-download -o taxonomy taxonomy  
 
-./deSPI-index test/refs/ref2tid.map taxonomy/nodes.dmp bin index
+./deSPI-index test/refs/ref2tid.map taxonomy/nodes.dmp bin index KMER_SIZE
 
 bin/deSPI classify index test/reads/reads.fa >Labels
 ```