diff --git a/src/main.cpp b/src/main.cpp
index e93f9d9..be80c4e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -127,7 +127,8 @@ int main(int argc, char* argv[]){
     cmd.add<string>("umi_loc", 0, "specify the location of UMI, can be (index1/index2/read1/read2/per_index/per_read, default is none", false, "");
     cmd.add<int>("umi_len", 0, "if the UMI is in read1/read2, its length should be provided", false, 0);
     cmd.add<string>("umi_prefix", 0, "if specified, an underline will be used to connect prefix and UMI (i.e. prefix=UMI, UMI=AATTCG, final=UMI_AATTCG). No prefix by default", false, "");
-    cmd.add<int>("umi_skip", 0, "if the UMI is in read1/read2, fastp can skip several bases following UMI, default is 0", false, 0);
+    cmd.add<int>("umi_skip", 0, "if the UMI is in read1/read2, fastp can skip several bases following UMI, default is 0", false, 0, cmdline::range(0, 100));
+    cmd.add<int>("umi_skipb", 0, "if the UMI is in read1/read2, fastp can skip several bases before trim UMI, default is 0", false, 0, cmdline::range(0, 100));
     cmd.add<string>("umi_delim", 0, "delimiter to use between the read name and the UMI, default is :", false, ":");
 
     // overrepresented sequence analysis
@@ -384,6 +385,7 @@ int main(int argc, char* argv[]){
     opt.umi.length = cmd.get<int>("umi_len");
     opt.umi.prefix = cmd.get<string>("umi_prefix");
     opt.umi.skip = cmd.get<int>("umi_skip");
+    opt.umi.skipb = cmd.get<int>("umi_skipb");
     opt.umi.delimiter = cmd.get<string>("umi_delim");
     if(opt.umi.enabled) {
         string umiLoc = cmd.get<string>("umi_loc");
diff --git a/src/options.h b/src/options.h
index 57086b2..6ae2348 100644
--- a/src/options.h
+++ b/src/options.h
@@ -108,6 +108,7 @@ class UMIOptions {
         location = UMI_LOC_NONE;
         length = 0;
         skip = 0;
+        skipb = 0;
         delimiter= ":";
     }
 public:
@@ -115,6 +116,7 @@ class UMIOptions {
     int location;
     int length;
     int skip;
+    int skipb;
     string prefix;
     string separator;
     string delimiter;
diff --git a/src/umiprocessor.cpp b/src/umiprocessor.cpp
index 4c2c829..8b8b548 100644
--- a/src/umiprocessor.cpp
+++ b/src/umiprocessor.cpp
@@ -18,12 +18,12 @@ void UmiProcessor::process(Read* r1, Read* r2) {
     else if(mOptions->umi.location == UMI_LOC_INDEX2 && r2)
         umi = r2->lastIndex();
     else if(mOptions->umi.location == UMI_LOC_READ1){
-        umi = r1->mSeq->substr(0, min(r1->length(), mOptions->umi.length));
-        r1->trimFront(umi.length() + mOptions->umi.skip);
+        umi = r1->mSeq->substr(mOptions->umi.skipb, min(r1->length(), mOptions->umi.length));
+        r1->trimFront(mOptions->umi.skipb + umi.length() + mOptions->umi.skip);
     }
     else if(mOptions->umi.location == UMI_LOC_READ2 && r2){
-        umi = r2->mSeq->substr(0, min(r2->length(), mOptions->umi.length));
-        r2->trimFront(umi.length() + mOptions->umi.skip);
+        umi = r2->mSeq->substr(mOptions->umi.skipb, min(r2->length(), mOptions->umi.length));
+        r2->trimFront(mOptions->umi.skipb + umi.length() + mOptions->umi.skip);
     }
     else if(mOptions->umi.location == UMI_LOC_PER_INDEX){
         string umiMerged = r1->firstIndex();
@@ -37,13 +37,13 @@ void UmiProcessor::process(Read* r1, Read* r2) {
         }
     }
     else if(mOptions->umi.location == UMI_LOC_PER_READ){
-        string umi1 = r1->mSeq->substr(0, min(r1->length(), mOptions->umi.length));
+        string umi1 = r1->mSeq->substr(mOptions->umi.skipb, min(r1->length(), mOptions->umi.length));
         string umiMerged = umi1;
-        r1->trimFront(umi1.length() + mOptions->umi.skip);
+        r1->trimFront(mOptions->umi.skipb + umi1.length() + mOptions->umi.skip);
         if(r2){
-            string umi2 = r2->mSeq->substr(0, min(r2->length(), mOptions->umi.length));
+            string umi2 = r2->mSeq->substr(mOptions->umi.skipb, min(r2->length(), mOptions->umi.length));
             umiMerged = umiMerged + "_" + umi2;
-            r2->trimFront(umi2.length() + mOptions->umi.skip);
+            r2->trimFront(mOptions->umi.skipb + umi2.length() + mOptions->umi.skip);
         }
 
         addUmiToName(r1, umiMerged);