diff --git a/src/atom.cpp b/src/atom.cpp
index 9fe115f5aa..796c0ba156 100644
--- a/src/atom.cpp
+++ b/src/atom.cpp
@@ -260,6 +260,7 @@ Atom::Atom(LAMMPS *lmp) : Pointers(lmp)
   map_hash = nullptr;
 
   unique_tags = nullptr;
+  reset_image_flag[0] = reset_image_flag[1] = reset_image_flag[2] = false;
 
   atom_style = nullptr;
   avec = nullptr;
@@ -1134,7 +1135,6 @@ void Atom::data_atoms(int n, char *buf, tagint id_offset, tagint mol_offset,
   // remap atom into simulation box
   // if atom is in my sub-domain, unpack its values
 
-  int flagx = 0, flagy = 0, flagz = 0;
   for (int i = 0; i < n; i++) {
     next = strchr(buf,'\n');
 
@@ -1154,9 +1154,9 @@ void Atom::data_atoms(int n, char *buf, tagint id_offset, tagint mol_offset,
       imz = utils::inumeric(FLERR,values[iptr+2],false,lmp);
       if ((domain->dimension == 2) && (imz != 0))
         error->all(FLERR,"Z-direction image flag must be 0 for 2d-systems");
-      if ((!domain->xperiodic) && (imx != 0)) { flagx = 1; imx = 0; }
-      if ((!domain->yperiodic) && (imy != 0)) { flagy = 1; imy = 0; }
-      if ((!domain->zperiodic) && (imz != 0)) { flagz = 1; imz = 0; }
+      if ((!domain->xperiodic) && (imx != 0)) { reset_image_flag[0] = true; imx = 0; }
+      if ((!domain->yperiodic) && (imy != 0)) { reset_image_flag[1] = true; imy = 0; }
+      if ((!domain->zperiodic) && (imz != 0)) { reset_image_flag[2] = true; imz = 0; }
     }
     imagedata = ((imageint) (imx + IMGMAX) & IMGMASK) |
         (((imageint) (imy + IMGMAX) & IMGMASK) << IMGBITS) |
@@ -1192,23 +1192,6 @@ void Atom::data_atoms(int n, char *buf, tagint id_offset, tagint mol_offset,
 
     buf = next + 1;
   }
-
-  // warn if reading data with non-zero image flags for non-periodic boundaries.
-  // we may want to turn this into an error at some point, since this essentially
-  // creates invalid position information that works by accident most of the time.
-
-  if (comm->me == 0) {
-    if (flagx)
-      error->warning(FLERR,"Non-zero imageflag(s) in x direction for "
-                           "non-periodic boundary reset to zero");
-    if (flagy)
-      error->warning(FLERR,"Non-zero imageflag(s) in y direction for "
-                           "non-periodic boundary reset to zero");
-    if (flagz)
-      error->warning(FLERR,"Non-zero imageflag(s) in z direction for "
-                           "non-periodic boundary reset to zero");
-  }
-
   delete [] values;
 }
 
diff --git a/src/atom.h b/src/atom.h
index e196d2d135..25a56de1c4 100644
--- a/src/atom.h
+++ b/src/atom.h
@@ -270,6 +270,10 @@ class Atom : protected Pointers {
 
   int *sametag;    // sametag[I] = next atom with same ID, -1 if no more
 
+  // true if image flags were reset to 0 during data_atoms()
+
+  bool reset_image_flag[3];
+
   // AtomVec factory types and map
 
   typedef AtomVec *(*AtomVecCreator)(LAMMPS *);
diff --git a/src/read_data.cpp b/src/read_data.cpp
index c17ab97229..edbfc16696 100644
--- a/src/read_data.cpp
+++ b/src/read_data.cpp
@@ -312,6 +312,10 @@ void ReadData::command(int narg, char **arg)
     error->all(FLERR,fmt::format("Cannot open file {}: {}",
                                  arg[0], utils::getsyserror()));
 
+  // reset so we can warn about reset image flags exactly once per data file
+
+  atom->reset_image_flag[0] = atom->reset_image_flag[1] = atom->reset_image_flag[2] = false;
+
   // first time system initialization
 
   if (addflag == NONE) {
@@ -1238,6 +1242,22 @@ void ReadData::atoms()
     nread += nchunk;
   }
 
+  // warn if we have read data with non-zero image flags for non-periodic boundaries.
+  // we may want to turn this into an error at some point, since this essentially
+  // creates invalid position information that works by accident most of the time.
+
+  if (comm->me == 0) {
+    if (atom->reset_image_flag[0])
+      error->warning(FLERR,"Non-zero imageflag(s) in x direction for "
+                           "non-periodic boundary reset to zero");
+    if (atom->reset_image_flag[1])
+      error->warning(FLERR,"Non-zero imageflag(s) in y direction for "
+                           "non-periodic boundary reset to zero");
+    if (atom->reset_image_flag[2])
+      error->warning(FLERR,"Non-zero imageflag(s) in z direction for "
+                           "non-periodic boundary reset to zero");
+  }
+
   // check that all atoms were assigned correctly
 
   bigint n = atom->nlocal;