diff --git a/src/verilog.y b/src/verilog.y
index 741b9d41b..25f65230b 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -1263,7 +1263,7 @@ package_or_generate_item_declaration<nodep>:    // ==IEEE: package_or_generate_i
         |       function_declaration                    { $$ = $1; }
         //UNSUP checker_declaration                     { $$ = $1; }
         |       dpi_import_export                       { $$ = $1; }
-        //UNSUP extern_constraint_declaration           { $$ = $1; }
+        |       extern_constraint_declaration           { $$ = $1; }
         |       class_declaration                       { $$ = $1; }
         //                      // class_constructor_declaration is part of function_declaration
         //                      // local_parameter_declaration under parameter_declaration
@@ -6877,9 +6877,10 @@ dist_item<nodep>:  // ==IEEE: dist_item + dist_weight
         |       value_range yP_COLONDIV expr            { $$ = $1; /*UNSUP-no-UVM*/ }
         ;
 
-//UNSUPextern_constraint_declaration:  // ==IEEE: extern_constraint_declaration
-//UNSUP         constraintStaticE yCONSTRAINT class_scope_id constraint_block   { }
-//UNSUP ;
+extern_constraint_declaration<nodep>:  // ==IEEE: extern_constraint_declaration
+                constraintStaticE yCONSTRAINT packageClassScopeE idAny
+                        { $$ = nullptr; BBUNSUP($<fl>2, "Unsupported: extern constraint"); }
+        ;
 
 constraintStaticE<cbool>:  // IEEE: part of extern_constraint_declaration
                 /* empty */                             { $$ = false; }
diff --git a/test_regress/t/t_randomize.out b/test_regress/t/t_randomize.out
index e46ab03c5..334f02e8a 100644
--- a/test_regress/t/t_randomize.out
+++ b/test_regress/t/t_randomize.out
@@ -8,4 +8,10 @@
 %Error-UNSUPPORTED: t/t_randomize.v:32:9: Unsupported: dist
    32 |       x dist { [100:102] :/ 1, 200 := 2, 300 := 5, 400};
       |         ^~~~
+%Error-UNSUPPORTED: t/t_randomize.v:37:1: Unsupported: extern constraint
+   37 | constraint Packet::ex { header > 0 };
+      | ^~~~~~~~~~
+%Error: t/t_randomize.v:37:23: syntax error, unexpected '{'
+   37 | constraint Packet::ex { header > 0 };
+      |                       ^
 %Error: Exiting due to
diff --git a/test_regress/t/t_randomize.v b/test_regress/t/t_randomize.v
index 9c3d9bf5e..30634b113 100644
--- a/test_regress/t/t_randomize.v
+++ b/test_regress/t/t_randomize.v
@@ -16,14 +16,14 @@ class Packet;
          header < (64'h1 << length);
       }
    }
-   constraint b {
+   constraint c {
       header >= length - 10;
       header <= length;
    }
-   constraint c {
+   constraint d {
       foreach (in_use[i]) {
          !(start_offset <= in_use[i].Xend_offsetX &&
-           start_offset + len - 1 >= in_use[i].Xstart_offsetX);
+           start_offset + length - 1 >= in_use[i].Xstart_offsetX);
       }
    }
    constraint order { solve length before header; }
@@ -34,6 +34,8 @@ class Packet;
 
 endclass
 
+constraint Packet::ex { header > 0 };
+
 module t (/*AUTOARG*/);
 
    Packet p;