diff --git a/script/cis-eQTL/low.ciseQTL.r b/script/cis-eQTL/low.ciseQTL.r
index 2e9bab9..84db0e9 100755
--- a/script/cis-eQTL/low.ciseQTL.r
+++ b/script/cis-eQTL/low.ciseQTL.r
@@ -1,6 +1,7 @@
 ### low.ciseQTL.R
 ### Calculate p-values of low-freq cis-eQTL via permutation
 #
+library(data.table)
 y=fread(Sys.getenv("gexp"))
 x=fread('low.Geno.data')
 idx=read.table('low.cispair.idx')