diff --git a/src/cluster/cluster.cpp b/src/cluster/cluster.cpp
index dfc090a0d9620fca665b6c059e48615fd8904862..ae4fae9fed32536d117bd990fb9c80ca30ac5c83 100644
--- a/src/cluster/cluster.cpp
+++ b/src/cluster/cluster.cpp
@@ -434,6 +434,11 @@ void cluster(const string& config_file, const string& data_file, const string& o
 	      p_outarray[myompthread] = p_output_2;
 	    }
 	    int jer = cluster_jxi488_cycle(myjxi488, sconf, gconf, p_scattering_angles, cid_2, p_output_2, output_path, vtppoanp_2);
+	  } else {
+	    if (myompthread > 0) {
+	      // If there is no input for this thread, set output pointer to NULL.
+	      p_outarray[myompthread] = NULL;
+	    }
 	  }
 #pragma omp barrier
 
@@ -616,7 +621,12 @@ void cluster(const string& config_file, const string& data_file, const string& o
 	    p_outarray[0] = p_output_2;
 	  }
 	  int jer = cluster_jxi488_cycle(myjxi488, sconf, gconf, p_scattering_angles, cid_2, p_output_2, output_path, vtppoanp_2);
-	} // close the OMP parallel for loop
+	} else {
+	  if (myompthread > 0) {
+	    // If there is no input for this thread, set the output pointer to NULL.
+	    p_outarray[myompthread] = NULL;
+	  }	  
+	}
 
 #pragma omp barrier
 	// threads different from 0 append their virtual files to the one of thread 0, and delete them