diff --git a/design_dump.cc b/design_dump.cc
index 9fa0ba876..f6540a6da 100644
--- a/design_dump.cc
+++ b/design_dump.cc
@@ -1124,7 +1124,10 @@ void NetAssign::dump(ostream&o, unsigned ind) const
       if (const NetExpr*de = get_delay())
 	    o << "#(" << *de << ") ";
 
-      o << *rval() << ";" << endl;
+      if (rval())
+	    o << *rval() << ";" << endl;
+      else
+	    o << "<rval elaboration error>;" << endl;
 }
 
 void NetAssignNB::dump(ostream&o, unsigned ind) const
@@ -1142,7 +1145,10 @@ void NetAssignNB::dump(ostream&o, unsigned ind) const
 	    o << *event_;
       }
 
-      o << *rval() << ";" << endl;
+      if (rval())
+	    o << *rval() << ";" << endl;
+      else
+	    o << "rval elaboration error>;" << endl;
 
 }
 
diff --git a/ivtest/ivltests/br_gh699.v b/ivtest/ivltests/br_gh699.v
new file mode 100644
index 000000000..841801109
--- /dev/null
+++ b/ivtest/ivltests/br_gh699.v
@@ -0,0 +1,9 @@
+
+// This should generate an error reporting the undef_func, but not segfault.
+module test1;
+   function [31:0] func1 (input [31:0] x);
+      return undef_func(x);
+   endfunction : func1
+
+   localparam X = func1(1);
+endmodule : test1
diff --git a/ivtest/regress-sv.list b/ivtest/regress-sv.list
index aa1b7517c..d28634ee3 100644
--- a/ivtest/regress-sv.list
+++ b/ivtest/regress-sv.list
@@ -210,6 +210,7 @@ br_gh568		normal,-g2009		ivltests
 br_gh661a		normal,-g2009		ivltests
 br_gh661b		normal,-g2009		ivltests
 br_gh672		normal,-g2009		ivltests
+br_gh699		CE,-g2009		ivltests
 br_ml20171017		normal,-g2009		ivltests
 br_ml20180227		CE,-g2009		ivltests
 br_ml20180309a		normal,-g2009		ivltests
diff --git a/net_func_eval.cc b/net_func_eval.cc
index 136be7805..58b7d629d 100644
--- a/net_func_eval.cc
+++ b/net_func_eval.cc
@@ -441,8 +441,11 @@ bool NetAssign::eval_func_lval_(const LineInfo&loc,
 bool NetAssign::evaluate_function(const LineInfo&loc,
 				  map<perm_string,LocalVar>&context_map) const
 {
-	// Evaluate the r-value expression.
-      NetExpr*rval_result = rval()->evaluate_function(loc, context_map);
+      // Evaluate the r-value expression.
+      const NetExpr*use_rval = rval();
+      if (use_rval == 0)
+	    return false;
+      NetExpr*rval_result = use_rval->evaluate_function(loc, context_map);
       if (rval_result == 0)
 	    return false;