diff --git a/src/verilog.y b/src/verilog.y
index 4170308ef..49377f202 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -7076,7 +7076,7 @@ coverage_option<nodep>:  // ==IEEE: coverage_option
                                   else {
                                       $<fl>1->v3error("Unknown coverage option name 'option."
                                                       << *$3 << "'"
-                                                      << "; not a valid option per IEEE 1800-2023 Table 19-1");
+                                                      << "; not a valid option (IEEE 1800-2023 Table 19-1)");
                                       valid = false;
                                   }
                               } else {
@@ -7099,7 +7099,7 @@ coverage_option<nodep>:  // ==IEEE: coverage_option
                                       } else {
                                           $<fl>1->v3error("Unknown coverage type option name 'type_option."
                                               << *$3 << "'"
-                                              << "; not a valid type option per IEEE 1800-2023 Table 19-3");
+                                              << "; not a valid type option (IEEE 1800-2023 Table 19-3)");
                                       }
                                       valid = false;
                                   }
@@ -7468,7 +7468,8 @@ coverage_eventE<nodep>:  // IEEE: [ coverage_event ]
                         { $$ = $1; }  // Keep the clocking event for automatic sampling
         |       yWITH__ETC yFUNCTION idAny/*"sample"*/ '(' tf_port_listE ')'
                         { if (*$3 != "sample") {
-                            $<fl>3->v3error("Coverage sampling function must be named 'sample'");
+                            $<fl>3->v3error("Coverage sampling function must be named 'sample'"
+                                            " (IEEE 1800-2023 19.8.1)");
                             $$ = nullptr;
                             DEL($5);
                           } else {
diff --git a/test_regress/t/t_covergroup_option_bad.out b/test_regress/t/t_covergroup_option_bad.out
index 6252ae205..b26b25d30 100644
--- a/test_regress/t/t_covergroup_option_bad.out
+++ b/test_regress/t/t_covergroup_option_bad.out
@@ -1,8 +1,8 @@
-%Error: t/t_covergroup_option_bad.v:12:5: Unknown coverage option name 'option.auto_bin_ma'; not a valid option per IEEE 1800-2023 Table 19-1
+%Error: t/t_covergroup_option_bad.v:12:5: Unknown coverage option name 'option.auto_bin_ma'; not a valid option (IEEE 1800-2023 Table 19-1)
    12 |     option.auto_bin_ma = 4;
       |     ^~~~~~
         ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
-%Error: t/t_covergroup_option_bad.v:19:7: Unknown coverage option name 'option.at_lest'; not a valid option per IEEE 1800-2023 Table 19-1
+%Error: t/t_covergroup_option_bad.v:19:7: Unknown coverage option name 'option.at_lest'; not a valid option (IEEE 1800-2023 Table 19-1)
    19 |       option.at_lest = 2;
       |       ^~~~~~
 %Error: t/t_covergroup_option_bad.v:25:5: 'type_option.auto_bin_max' is not valid; use 'option.auto_bin_max' instead
@@ -11,7 +11,7 @@
 %Error: t/t_covergroup_option_bad.v:32:7: 'type_option.at_least' is not valid; use 'option.at_least' instead
    32 |       type_option.at_least = 2;
       |       ^~~~~~~~~~~
-%Error: t/t_covergroup_option_bad.v:38:5: Unknown coverage type option name 'type_option.bogus'; not a valid type option per IEEE 1800-2023 Table 19-3
+%Error: t/t_covergroup_option_bad.v:38:5: Unknown coverage type option name 'type_option.bogus'; not a valid type option (IEEE 1800-2023 Table 19-3)
    38 |     type_option.bogus = 1;
       |     ^~~~~~~~~~~
 %Error: Exiting due to
diff --git a/test_regress/t/t_covergroup_with_function_foo_bad.out b/test_regress/t/t_covergroup_with_function_foo_bad.out
index dbbe6ec1a..477675929 100644
--- a/test_regress/t/t_covergroup_with_function_foo_bad.out
+++ b/test_regress/t/t_covergroup_with_function_foo_bad.out
@@ -1,4 +1,4 @@
-%Error: t/t_covergroup_with_function_foo_bad.v:8:35: Coverage sampling function must be named 'sample'
+%Error: t/t_covergroup_with_function_foo_bad.v:8:35: Coverage sampling function must be named 'sample' (IEEE 1800-2023 19.8.1)
     8 |   covergroup cg_bad with function foo(int x);
       |                                   ^~~
         ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.