diff --git a/src/region_intersect.cpp b/src/region_intersect.cpp
index 1da6d63be7..c89ee91574 100644
--- a/src/region_intersect.cpp
+++ b/src/region_intersect.cpp
@@ -31,13 +31,18 @@ RegIntersect::RegIntersect(LAMMPS *lmp, int narg, char **arg) :
   options(narg-(n+3),&arg[n+3]);
 
   // build list of regions to intersect
+  // store sub-region IDs in idsub
 
+  idsub = new char*[n];
   list = new int[n];
   nregion = 0;
 
   int iregion;
   for (int iarg = 0; iarg < n; iarg++) {
-    iregion = domain->find_region(arg[iarg+3]);
+    n = strlen(arg[iarg+3]) + 1;
+    idsub[nregion] = new char[n];
+    strcpy(idsub[nregion],arg[iarg+3]);
+    iregion = domain->find_region(idsub[nregion]);
     if (iregion == -1) 
       error->all(FLERR,"Region intersect region ID does not exist");
     list[nregion++] = iregion;
@@ -92,6 +97,8 @@ RegIntersect::RegIntersect(LAMMPS *lmp, int narg, char **arg) :
 
 RegIntersect::~RegIntersect()
 {
+  for (int ilist = 0; ilist < nregion; ilist++) delete [] idsub[ilist];
+  delete [] idsub;
   delete [] list;
   delete [] contact;
 }
@@ -101,6 +108,20 @@ RegIntersect::~RegIntersect()
 void RegIntersect::init()
 {
   Region::init();
+
+  // re-build list of sub-regions in case other regions were deleted
+  // error if a sub-region was deleted
+
+  int iregion;
+  for (int ilist = 0; ilist < nregion; ilist++) {
+    iregion = domain->find_region(idsub[ilist]);
+    if (iregion == -1) 
+      error->all(FLERR,"Region union region ID does not exist");
+    list[ilist] = iregion;
+  }
+
+  // init the sub-regions
+
   Region **regions = domain->regions;
   for (int ilist = 0; ilist < nregion; ilist++)
     regions[list[ilist]]->init();
diff --git a/src/region_intersect.h b/src/region_intersect.h
index 62946a65c0..52d3e208de 100644
--- a/src/region_intersect.h
+++ b/src/region_intersect.h
@@ -38,6 +38,7 @@ class RegIntersect : public Region {
  private:
   int nregion;
   int *list;
+  char **idsub;
 };
 
 }
diff --git a/src/region_union.cpp b/src/region_union.cpp
index e9fc4ef680..83a550b5bd 100644
--- a/src/region_union.cpp
+++ b/src/region_union.cpp
@@ -31,14 +31,19 @@ RegUnion::RegUnion(LAMMPS *lmp, int narg, char **arg) : Region(lmp, narg, arg)
   if (n < 2) error->all(FLERR,"Illegal region command");
   options(narg-(n+3),&arg[n+3]);
 
-  // build list of regions to union
+  // build list of region indices to union
+  // store sub-region IDs in idsub
 
+  idsub = new char*[n];
   list = new int[n];
   nregion = 0;
 
   int iregion;
   for (int iarg = 0; iarg < n; iarg++) {
-    iregion = domain->find_region(arg[iarg+3]);
+    n = strlen(arg[iarg+3]) + 1;
+    idsub[nregion] = new char[n];
+    strcpy(idsub[nregion],arg[iarg+3]);
+    iregion = domain->find_region(idsub[nregion]);
     if (iregion == -1) 
       error->all(FLERR,"Region union region ID does not exist");
     list[nregion++] = iregion;
@@ -84,6 +89,8 @@ RegUnion::RegUnion(LAMMPS *lmp, int narg, char **arg) : Region(lmp, narg, arg)
 
 RegUnion::~RegUnion()
 {
+  for (int ilist = 0; ilist < nregion; ilist++) delete [] idsub[ilist];
+  delete [] idsub;
   delete [] list;
   delete [] contact;
 }
@@ -93,6 +100,20 @@ RegUnion::~RegUnion()
 void RegUnion::init()
 {
   Region::init();
+
+  // re-build list of sub-regions in case other regions were deleted
+  // error if a sub-region was deleted
+
+  int iregion;
+  for (int ilist = 0; ilist < nregion; ilist++) {
+    iregion = domain->find_region(idsub[ilist]);
+    if (iregion == -1) 
+      error->all(FLERR,"Region union region ID does not exist");
+    list[ilist] = iregion;
+  }
+
+  // init the sub-regions
+
   Region **regions = domain->regions;
   for (int ilist = 0; ilist < nregion; ilist++)
     regions[list[ilist]]->init();
diff --git a/src/region_union.h b/src/region_union.h
index 6d0ec063cf..664d9f3394 100644
--- a/src/region_union.h
+++ b/src/region_union.h
@@ -38,6 +38,7 @@ class RegUnion : public Region {
  private:
   int nregion;
   int *list;
+  char **idsub;
 };
 
 }