diff --git a/src/rssm.cpp b/src/rssm.cpp
index da4753859f2ae66ea6b6b788a045b516c095e225..14de1619cca799fc5aa0aa5c4d637295e1d7fccd 100644
--- a/src/rssm.cpp
+++ b/src/rssm.cpp
@@ -461,13 +461,11 @@ void NRSSM::ReadSeries( int flag )
     printf( "used %i detectors\n", ndet );
     double tstep = RR[0].daq_time_step;
     bool incremental_in = RR[0].incremental;
-    int nE = RR[0].rawdata[0].size()/(ndet+2);
 
     for( isub=1; isub<nsub; ++isub ){
         if( RR[isub].angles.size()!=ndet ||
             RR[isub].daq_time_step!=tstep ||
-            RR[isub].incremental!=incremental_in ||
-            RR[0].rawdata[0].size()/(ndet+2)!=nE ){
+            RR[isub].incremental!=incremental_in ){
             printf( "SEVERE essential parameters are inconsistent\n" );
             return;
         }
@@ -475,7 +473,7 @@ void NRSSM::ReadSeries( int flag )
 
     // Set file headers:
     COld olf[2];
-    int iolf, j;
+    int iolf, j, nE;
 
     for( iolf=0; iolf<2; ++iolf ){
         olf[iolf].lDoc.push_back( "acquire data from series"+fser );
@@ -506,6 +504,7 @@ void NRSSM::ReadSeries( int flag )
     }
 
     if( RR[0].maj_outform>=3 ){
+        nE = RR[0].rawdata[0].size()/(1+ndet*2);
         // Reverse incrementation?
         if( incremental_in ){
             printf( "reversing incrementation\n" );
@@ -552,6 +551,7 @@ void NRSSM::ReadSeries( int flag )
         }
 
     } else {
+        nE = RR[0].rawdata[0].size()/(ndet+2);
         // Reverse incrementation?
         if( incremental_in ){
             printf( "reversing incrementation\n" );