diff --git a/wrappers/wrappers/macs2/callpeak/wrapper.py b/wrappers/wrappers/macs2/callpeak/wrapper.py
index d90c17d6..1a6b7b0d 100644
--- a/wrappers/wrappers/macs2/callpeak/wrapper.py
+++ b/wrappers/wrappers/macs2/callpeak/wrapper.py
@@ -15,7 +15,7 @@
 
 genome_count_flag = ''
 if effective_genome_count != '':
-    genome_count_flag = ' -g ' + effective_genome_count + ' '
+    genome_count_flag = '-g ' + str(effective_genome_count)
 
 cmds = (
     'macs2 '