diff --git a/c_source/pruning/pruneVoids.cpp b/c_source/pruning/pruneVoids.cpp
index 534abc0..d4a08aa 100644
--- a/c_source/pruning/pruneVoids.cpp
+++ b/c_source/pruning/pruneVoids.cpp
@@ -81,7 +81,7 @@ typedef struct voidStruct {
   float center[3], macrocenter[3];
   int accepted;
   int voidType;
-  int parentID, numChildren, level;
+  int parentIndx, numChildren, level;
   bool isLeaf, hasHighCentralDen;
   gsl_vector *eval;
   gsl_matrix *evec;
@@ -339,8 +339,8 @@ int main(int argc, char **argv) {
 
     voids[i-1].isLeaf = true;
     voids[i-1].hasHighCentralDen = false;
+    voids[i-1].parentIndx = -1;  
     voids[i-1].numChildren = 0;
-    voids[i-1].parentID = -1;  
     voids[i-1].level = 0;  
 
     voids[i-1].eval = gsl_vector_alloc(3);
@@ -515,7 +515,7 @@ int main(int argc, char **argv) {
       }
  
       if (allZonesMatch) {
-        voids[iVoid].parentID = checkID;
+        voids[iVoid].parentIndx = iCheck;
         voids[iCheck].numChildren++;
       }
     }
@@ -525,17 +525,10 @@ int main(int argc, char **argv) {
   // compute level in tree
   for (iVoid = 0; iVoid < numVoids; iVoid++) {
     int level = 0;
-    int parentID = voids[iVoid].parentID;
-    while (parentID != -1) {
+    int parentIndx = voids[iVoid].parentIndx;
+    while (parentIndx != -1) {
       level++;
-
-      // find the index of the parent
-      for (i = 0; i < numVoids; i++) {
-        if (voids[i].voidID == parentID) {
-          parentID = voids[i].voidID;
-          break;
-        }
-      }
+      parentIndx = voids[parentIndx].parentIndx;
     }
     voids[iVoid].level = level;
   }
@@ -951,7 +944,7 @@ int main(int argc, char **argv) {
   numAreParents = 0;
   iGood = 0;
   for (iVoid = 0; iVoid < voids.size(); iVoid++) {
-    if (voids[iVoid].parentID != -1) {
+    if (voids[iVoid].parentIndx != -1) {
       numAreParents++;
       voids[iVoid].isLeaf = true;
      } else {
@@ -1039,7 +1032,7 @@ void openFiles(string outputDir, string sampleName,
   *fpBarycenter = fopen((outputDir+"/"+prefix+"macrocenters_"+dataPortion+"_"+sampleName).c_str(), "w");
 
   *fpCenters = fopen((outputDir+"/"+prefix+"centers_"+dataPortion+"_"+sampleName).c_str(), "w");
-  fprintf(*fpCenters, "# center x,y,z (Mpc/h), volume (normalized), radius (Mpc/h), redshift, volume (Mpc/h^3), void ID, density contrast, num part, parent ID, tree level, number of children, central density\n");
+  fprintf(*fpCenters, "# center x,y,z (Mpc/h), volume (normalized), radius (Mpc/h), redshift, volume (Mpc/h^3), void ID, density contrast, num part, parent index, tree level, number of children, central density\n");
 
   *fpSkyPositions = fopen((outputDir+"/"+prefix+"sky_positions_"+dataPortion+"_"+sampleName).c_str(), "w");
   fprintf(*fpSkyPositions, "# RA, dec, redshift, radius (Mpc/h), void ID\n");
@@ -1145,7 +1138,7 @@ void outputVoids(string outputDir, string sampleName, string prefix,
              outVoid.voidID,
              outVoid.densCon,
              outVoid.numPart,
-             outVoid.parentID,
+             outVoid.parentIndx,
              outVoid.level,
              outVoid.numChildren,
              outVoid.centralDen);