diff --git a/src/write_data.cpp b/src/write_data.cpp
index 7047aacfd4..decc92ea8c 100644
--- a/src/write_data.cpp
+++ b/src/write_data.cpp
@@ -177,6 +177,17 @@ void WriteData::write(char *file)
     MPI_Allreduce(&nimpropers_local,&nimpropers,1,MPI_LMP_BIGINT,MPI_SUM,world);
   }
 
+  // check for bonus data.
+  if (me == 0) {
+    if ((atom->nellipsoids > 0)
+        || (atom->nlines > 0)
+        || (atom->ntris > 0)
+        || (atom->nbodies > 0))
+      error->warning(FLERR,"System has ellipsoids, lines, triangles, or bodies. "
+                     "Those are not yet supported by write_data. The data file "
+                     "will thus be incomplete.");
+  }
+
   // open data file
 
   if (me == 0) {