diff --git a/src/FqMainBackend.cpp b/src/FqMainBackend.cpp
index 777a02a4ab1a2d8b793e70b1ea2bca4ceaa4cff8..7ef1104082cbed9632a2a49069f40fdcfd986546 100644
--- a/src/FqMainBackend.cpp
+++ b/src/FqMainBackend.cpp
@@ -107,7 +107,7 @@ void FqMainBackend::processBuf(char * buf,int nread,unsigned char f_id,unsigned
 #ifdef DEBUG
                 cout<<"nread="<<nread<<endl;
                 cout<<"cnt="<<cnt<<endl;
-	        cout<<"rstart_offset="<<rstart_offset<<endl;
+	            cout<<"rstart_offset="<<rstart_offset<<endl;
                 is_id=1;
                 idx_id=0;
                 nb_start++;
@@ -136,6 +136,7 @@ void FqMainBackend::processBuf(char * buf,int nread,unsigned char f_id,unsigned
                         // if (eof) cout<<"warning, reached eof in file PE2 after: "<<nb_read_PE1<<" reads in PE1"<<endl;
                         st+=pe2info.score;
                         unsigned long j=rstart_offset/INT_MAX;
+                        if (pe2info.rstart_offset/INT_MAX!=j) throw std::runtime_error("Inconsistency between offset values in PE files!");
                         update_rpos(pe2info.f_id,pe2info.rstart_offset,j,&rp);
 #ifdef DEBUG
                     nb_stop++;