diff --git a/Changes b/Changes
index 3377a875b..10f50d405 100644
--- a/Changes
+++ b/Changes
@@ -27,7 +27,8 @@ Verilator 4.215 devel
 * Fix display of empty string constant (#3207). [Julie Schwartz]
 * Fix incorrect width after and-or optimization (#3208). [Julie Schwartz]
 * Fix $fopen etc on integer arrays (#3214). [adrienlemasle]
-* Fix %0 format on $value$plusargs.
+* Fix $size on dynamic strings (#3216).
+* Fix %0 format on $value$plusargs (#3217).
 
 
 Verilator 4.214 2021-10-17
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index efb66f75b..15df19767 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -1351,7 +1351,8 @@ private:
         case AstAttrType::DIM_RIGHT:
         case AstAttrType::DIM_SIZE: {
             UASSERT_OBJ(nodep->fromp() && nodep->fromp()->dtypep(), nodep, "Unsized expression");
-            if (VN_IS(nodep->fromp()->dtypep(), QueueDType)) {
+            AstNodeDType* const dtypep = nodep->fromp()->dtypep();
+            if (VN_IS(dtypep, QueueDType)) {
                 switch (nodep->attrType()) {
                 case AstAttrType::DIM_SIZE: {
                     AstNode* const newp = new AstCMethodHard(
@@ -1398,26 +1399,34 @@ private:
                 default: nodep->v3error("Unhandled attribute type");
                 }
             } else {
-                std::pair<uint32_t, uint32_t> dimpair
-                    = nodep->fromp()->dtypep()->skipRefp()->dimensions(true);
-                uint32_t msbdim = dimpair.first + dimpair.second;
+                const std::pair<uint32_t, uint32_t> dimpair = dtypep->skipRefp()->dimensions(true);
+                const uint32_t msbdim = dimpair.first + dimpair.second;
                 if (!nodep->dimp() || msbdim < 1) {
-                    const int dim = 1;
-                    AstConst* const newp = dimensionValue(
-                        nodep->fileline(), nodep->fromp()->dtypep(), nodep->attrType(), dim);
-                    nodep->replaceWith(newp);
-                    VL_DO_DANGLING(nodep->deleteTree(), nodep);
+                    if (VN_IS(dtypep, BasicDType) && dtypep->basicp()->isString()) {
+                        // IEEE undocumented but $bits(string) must give length(string) * 8
+                        AstNode* const newp = new AstShiftL{
+                            nodep->fileline(),
+                            new AstLenN{nodep->fileline(), nodep->fromp()->unlinkFrBack()},
+                            new AstConst{nodep->fileline(), 3},  // * 8
+                            32};
+                        nodep->replaceWith(newp);
+                        VL_DO_DANGLING(pushDeletep(nodep), nodep);
+                    } else {
+                        const int dim = 1;
+                        AstConst* const newp
+                            = dimensionValue(nodep->fileline(), dtypep, nodep->attrType(), dim);
+                        nodep->replaceWith(newp);
+                        VL_DO_DANGLING(nodep->deleteTree(), nodep);
+                    }
                 } else if (VN_IS(nodep->dimp(), Const)) {
                     const int dim = VN_AS(nodep->dimp(), Const)->toSInt();
-                    AstConst* const newp = dimensionValue(
-                        nodep->fileline(), nodep->fromp()->dtypep(), nodep->attrType(), dim);
+                    AstConst* const newp
+                        = dimensionValue(nodep->fileline(), dtypep, nodep->attrType(), dim);
                     nodep->replaceWith(newp);
                     VL_DO_DANGLING(nodep->deleteTree(), nodep);
                 } else {  // Need a runtime lookup table.  Yuk.
-                    UASSERT_OBJ(nodep->fromp() && nodep->fromp()->dtypep(), nodep,
-                                "Unsized expression");
-                    AstVar* const varp
-                        = dimensionVarp(nodep->fromp()->dtypep(), nodep->attrType(), msbdim);
+                    UASSERT_OBJ(nodep->fromp() && dtypep, nodep, "Unsized expression");
+                    AstVar* const varp = dimensionVarp(dtypep, nodep->attrType(), msbdim);
                     AstNode* const dimp = nodep->dimp()->unlinkFrBack();
                     AstVarRef* const varrefp
                         = new AstVarRef(nodep->fileline(), varp, VAccess::READ);
diff --git a/test_regress/t/t_string_size.out b/test_regress/t/t_string_size.out
new file mode 100644
index 000000000..cd674d097
--- /dev/null
+++ b/test_regress/t/t_string_size.out
@@ -0,0 +1,4 @@
+>< == ><
+>< == ><
+> < == > <
+*-* All Finished *-*
diff --git a/test_regress/t/t_string_size.pl b/test_regress/t/t_string_size.pl
new file mode 100755
index 000000000..03b63c1a0
--- /dev/null
+++ b/test_regress/t/t_string_size.pl
@@ -0,0 +1,22 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2021 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(simulator => 1);
+
+compile(
+    );
+
+execute(
+    check_finished => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_string_size.v b/test_regress/t/t_string_size.v
new file mode 100644
index 000000000..f9d87caa3
--- /dev/null
+++ b/test_regress/t/t_string_size.v
@@ -0,0 +1,27 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2021 by wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t;
+   parameter string ES = "";
+   parameter EI = "";  // B is an integer of width 8
+   parameter string OS = "O";
+   parameter OI = "O";  // B is an integer of width 8
+
+   initial begin
+      $display(">< == >%s<", "");
+      $display(">< == >%s<", ES);
+      $display("> < == >%s<", EI);
+
+      if ($bits("") != 0) $stop;
+      if ($bits("A") != 8) $stop;
+      if ($bits(ES) != 0) $stop;
+      if ($bits(OS) != 8) $stop;
+      if ($bits(OI) != 8) $stop;
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule