diff --git a/elab_expr.cc b/elab_expr.cc
index 29a39c016..ea112eff4 100644
--- a/elab_expr.cc
+++ b/elab_expr.cc
@@ -444,6 +444,13 @@ NetExpr* PEConcat::elaborate_expr(Design*des, NetScope*scope, bool) const
 		  return 0;
 	    }
 
+	    if (rep->value().is_zero()) {
+		  cerr << get_line() << ": error: Concatenation repeat "
+		       << "may not be zero." << endl;
+		  des->errors += 1;
+		  return 0;
+	    }
+
 	    repeat = rep;
       }
 
diff --git a/elab_net.cc b/elab_net.cc
index 8f5a311db..1a01e8057 100644
--- a/elab_net.cc
+++ b/elab_net.cc
@@ -1357,6 +1357,13 @@ NetNet* PEConcat::elaborate_net(Design*des, NetScope*scope,
 		  des->errors += 1;
 		  return 0;
 	    }
+
+	    if (erep->value().is_zero()) {
+		  cerr << get_line() << ": error: Concatenation repeat "
+		       << "may not be zero." << endl;
+		  des->errors += 1;
+		  return 0;
+	    }
       }
 
 	/* The operands of the concatenation must contain all