diff --git a/workflow/rules/common.smk b/workflow/rules/common.smk
index d443bd3..1726d09 100644
--- a/workflow/rules/common.smk
+++ b/workflow/rules/common.smk
@@ -20,7 +20,7 @@ def get_samples(samplesFile):
 # read in the samples file, we assume that they are in this order: sample\tbam/cram\tindex    
 def read_samplesFile(samplesFile): 
     samplesTable = pd.read_table(samplesFile, sep="\t", 
-                   header='infer')
+                   header='infer', dtype=str)
     return(samplesTable)