diff --git a/src/pair_hybrid_scaled.cpp b/src/pair_hybrid_scaled.cpp
index cdbccbf7c7..de8801fe24 100644
--- a/src/pair_hybrid_scaled.cpp
+++ b/src/pair_hybrid_scaled.cpp
@@ -396,6 +396,9 @@ double PairHybridScaled::single(int i, int j, int itype, int jtype, double rsq,
     double *vals = new double[nvars];
     for (i = 0; i < nvars; ++i) {
       j = input->variable->find(scalevars[i].c_str());
+      if (j < 0)
+        error->all(FLERR,fmt::format("Variable '{}' not found when updating "
+                                     "scale factors",scalevars[i]));
       vals[i] = input->variable->compute_equal(j);
     }
     for (i = 0; i < nstyles; ++i) {