diff --git a/tools/sr_mapping/bowtie_wrapper.xml b/tools/sr_mapping/bowtie_wrapper.xml
index 1a4aa4ba40b..501f7326262 100644
--- a/tools/sr_mapping/bowtie_wrapper.xml
+++ b/tools/sr_mapping/bowtie_wrapper.xml
@@ -2,7 +2,7 @@
   <description></description>
   <command interpreter="python">
     bowtie_wrapper.py 
-    --threads="8"
+    --threads="4"
     --input1=$singlePaired.input1
     #if $singlePaired.sPaired == "paired":
      --input2=$singlePaired.input2
diff --git a/tools/sr_mapping/bwa_wrapper.xml b/tools/sr_mapping/bwa_wrapper.xml
index cce9ab95169..3e10808553e 100644
--- a/tools/sr_mapping/bwa_wrapper.xml
+++ b/tools/sr_mapping/bwa_wrapper.xml
@@ -2,7 +2,7 @@
   <description></description>
   <command interpreter="python">
     bwa_wrapper.py 
-    --threads="8"
+    --threads="4"
     #if $solidOrSolexa.solidRefGenomeSource.refGenomeSource == "history":
      --ref=$solidOrSolexa.solidRefGenomeSource.ownFile
     #else: