diff --git a/src/V3AstNodeExpr.h b/src/V3AstNodeExpr.h
index 8014553d1..374483b85 100644
--- a/src/V3AstNodeExpr.h
+++ b/src/V3AstNodeExpr.h
@@ -4872,7 +4872,7 @@ public:
     }
     ASTGEN_MEMBERS_AstCvtPackString;
     void numberOperate(V3Number& out, const V3Number& lhs) override { out.opAssign(lhs); }
-    string emitVerilog() override { return "%f$_CAST(%l)"; }
+    string emitVerilog() override { V3ERROR_NA_RETURN(""); }
     string emitC() override { V3ERROR_NA_RETURN(""); }
     bool cleanOut() const override { return true; }
     bool cleanLhs() const override { return true; }
diff --git a/src/V3EmitCFunc.h b/src/V3EmitCFunc.h
index efdd2958c..f14b483e6 100644
--- a/src/V3EmitCFunc.h
+++ b/src/V3EmitCFunc.h
@@ -864,7 +864,7 @@ public:
         switch (nodep->ctlType()) {
         case VDumpCtlType::FILE:
             putns(nodep, "vlSymsp->_vm_contextp__->dumpfile(");
-            emitCvtPackStr(nodep->exprp());
+            iterateConst(nodep->exprp());
             puts(");\n");
             break;
         case VDumpCtlType::VARS:
@@ -927,7 +927,7 @@ public:
         puts("(");
         puts(cvtToStr(nodep->outp()->widthMin()));
         puts(", ");
-        emitCvtPackStr(nodep->searchp());
+        iterateConst(nodep->searchp());
         puts(", ");
         putbs("");
         iterateAndNextConstNull(nodep->outp());
@@ -935,7 +935,7 @@ public:
     }
     void visit(AstTestPlusArgs* nodep) override {
         putns(nodep, "VL_TESTPLUSARGS_I(");
-        emitCvtPackStr(nodep->searchp());
+        iterateConst(nodep->searchp());
         puts(")");
     }
     void visit(AstFError* nodep) override {
@@ -965,16 +965,14 @@ public:
     }
     void visit(AstFOpen* nodep) override {
         putns(nodep, "VL_FOPEN_NN(");
-        emitCvtPackStr(nodep->filenamep());
+        iterateConst(nodep->filenamep());
         putbs(", ");
-        if (nodep->modep()->width() > 4 * 8)
-            nodep->modep()->v3error("$fopen mode should be <= 4 characters");
-        emitCvtPackStr(nodep->modep());
+        iterateConst(nodep->modep());
         puts(");\n");
     }
     void visit(AstFOpenMcd* nodep) override {
         putns(nodep, "VL_FOPEN_MCD_N(");
-        emitCvtPackStr(nodep->filenamep());
+        iterateConst(nodep->filenamep());
         puts(");\n");
     }
     void visit(AstNodeReadWriteMem* nodep) override {
@@ -1004,7 +1002,7 @@ public:
             }
         }
         putbs(", ");
-        emitCvtPackStr(nodep->filenamep());
+        iterateConst(nodep->filenamep());
         putbs(", ");
         {
             const bool need_ptr = !VN_IS(nodep->memp()->dtypep(), AssocArrayDType);
@@ -1297,7 +1295,7 @@ public:
         puts(", ");
         if (nodep->suffixp()) {
             puts("true, ");
-            emitCvtPackStr(nodep->suffixp());
+            iterateAndNextConstNull(nodep->suffixp());
         } else {
             puts("false, \"\"");
         }
diff --git a/src/V3EmitV.cpp b/src/V3EmitV.cpp
index 9b6f052a6..63bed1b20 100644
--- a/src/V3EmitV.cpp
+++ b/src/V3EmitV.cpp
@@ -283,6 +283,16 @@ class EmitVBaseVisitorConst VL_NOT_FINAL : public VNVisitorConst {
     void visit(AstCoverInc*) override {}  // N/A
     void visit(AstCoverToggle*) override {}  // N/A
 
+    void visit(AstCvtPackString* nodep) override {
+        putfs(nodep, "");
+        if (AstConst* const lhsConstp = VN_CAST(nodep->lhsp(), Const)) {
+            putsQuoted(lhsConstp->num().toString());
+        } else {
+            puts("string'(");
+            iterateAndNextConstNull(nodep->lhsp());
+            puts(")");
+        }
+    }
     void visit(AstTestPlusArgs* nodep) override {
         putfs(nodep, nodep->verilogKwd());
         putbs("(");
@@ -292,7 +302,9 @@ class EmitVBaseVisitorConst VL_NOT_FINAL : public VNVisitorConst {
     void visit(AstValuePlusArgs* nodep) override {
         putfs(nodep, nodep->verilogKwd());
         putbs("(");
-        iterateChildrenConst(nodep);
+        iterateConstNull(nodep->searchp());
+        putbs(", ");
+        iterateConstNull(nodep->outp());
         puts(")");
     }
     void visitNodeDisplay(AstNode* nodep, AstNode* fileOrStrgp, const string& text,
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index 97cbbf73c..0cc6fd188 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -5893,17 +5893,16 @@ class WidthVisitor final : public VNVisitor {
     }
     void visit(AstDumpCtl* nodep) override {
         assertAtStatement(nodep);
-        // Just let all arguments seek their natural sizes
-        userIterateChildren(nodep, WidthVP{SELF, BOTH}.p());
+        if (nodep->exprp()) iterateCheckString(nodep, "LHS", nodep->exprp(), BOTH);
     }
     void visit(AstFOpen* nodep) override {
         // Although a system function in IEEE, here a statement which sets the file pointer (MCD)
-        userIterateAndNext(nodep->filenamep(), WidthVP{SELF, BOTH}.p());
-        userIterateAndNext(nodep->modep(), WidthVP{SELF, BOTH}.p());
+        iterateCheckString(nodep, "filename", nodep->filenamep(), BOTH);
+        iterateCheckString(nodep, "mode", nodep->modep(), BOTH);
         nodep->dtypeSetLogicUnsized(32, 1, VSigning::SIGNED);  // Spec says integer return
     }
     void visit(AstFOpenMcd* nodep) override {
-        userIterateAndNext(nodep->filenamep(), WidthVP{SELF, BOTH}.p());
+        iterateCheckString(nodep, "filename", nodep->filenamep(), BOTH);
         nodep->dtypeSetLogicUnsized(32, 1, VSigning::SIGNED);  // Spec says integer return
     }
     void visit(AstFClose* nodep) override {
@@ -6005,7 +6004,7 @@ class WidthVisitor final : public VNVisitor {
     }
     void visit(AstNodeReadWriteMem* nodep) override {
         assertAtStatement(nodep);
-        userIterateAndNext(nodep->filenamep(), WidthVP{SELF, BOTH}.p());
+        iterateCheckString(nodep, "filename", nodep->filenamep(), BOTH);
         userIterateAndNext(nodep->memp(), WidthVP{SELF, BOTH}.p());
         const AstNodeDType* subp = nullptr;
         if (const AstAssocArrayDType* adtypep
@@ -6037,13 +6036,13 @@ class WidthVisitor final : public VNVisitor {
     }
     void visit(AstTestPlusArgs* nodep) override {
         if (m_vup->prelim()) {
-            userIterateAndNext(nodep->searchp(), WidthVP{SELF, BOTH}.p());
+            iterateCheckString(nodep, "LHS", nodep->searchp(), BOTH);
             nodep->dtypeChgWidthSigned(32, 1, VSigning::SIGNED);  // Spec says integer return
         }
     }
     void visit(AstValuePlusArgs* nodep) override {
         if (m_vup->prelim()) {
-            userIterateAndNext(nodep->searchp(), WidthVP{SELF, BOTH}.p());
+            iterateCheckString(nodep, "LHS", nodep->searchp(), BOTH);
             userIterateAndNext(nodep->outp(), WidthVP{SELF, BOTH}.p());
             nodep->dtypeChgWidthSigned(32, 1, VSigning::SIGNED);  // Spec says integer return
         }
diff --git a/test_regress/t/t_debug_emitv.out b/test_regress/t/t_debug_emitv.out
index aedb5a5ea..a5071f8e0 100644
--- a/test_regress/t/t_debug_emitv.out
+++ b/test_regress/t/t_debug_emitv.out
@@ -40,7 +40,7 @@ module Vt_debug_emitv_t;
     Iface the_ifaces[3:0] ();
     initial begin
         begin
-            if ($test$plusargs(40'h48454c4c4f)) begin
+            if ($test$plusargs("HELLO")) begin
                 $display("Hello argument found.");
             end
             if ((Pkg::FOO == 'sh0)) begin
@@ -49,7 +49,7 @@ module Vt_debug_emitv_t;
             if ((ZERO == 'sh0)) begin
                 $write("");
             end
-            if ($value$plusargs(56'h544553543d2564i1)) begin
+            if ($value$plusargs("TEST=%d", i1)) begin
                 $display("value was %~", i1);
             end
             else begin
@@ -185,10 +185,10 @@ module Vt_debug_emitv_t;
                                  : $c('sh1e)));
             $c(;);
             $display("%d", $c(0));
-            fd = $fopen(72'h2f6465762f6e756c6c);
+            fd = $fopen("/dev/null");
             ;
             $fclose(fd);
-            fd = $fopen(72'h2f6465762f6e756c6c, 8'h72);
+            fd = $fopen("/dev/null", "r");
             ;
             $fgetc(fd);
             $fflush(fd);
@@ -196,9 +196,9 @@ module Vt_debug_emitv_t;
             ;
             $fdisplay(32'h69203d20, "%~", sum);
             $fwrite(fd, "hello");
-            $readmemh(fd, array);
-            $readmemh(fd, array, 'sh0);
-            $readmemh(fd, array, 'sh0, 'sh0);
+            $readmemh(string'(fd), array);
+            $readmemh(string'(fd), array, 'sh0);
+            $readmemh(string'(fd), array, 'sh0, 'sh0);
             sum = 'sh0;
             begin : unnamedblk3
                 int signed i;
diff --git a/test_regress/t/t_sys_fopen_bad.out b/test_regress/t/t_sys_fopen_bad.out
deleted file mode 100644
index 53525cf73..000000000
--- a/test_regress/t/t_sys_fopen_bad.out
+++ /dev/null
@@ -1,5 +0,0 @@
-%Error: t/t_sys_fopen_bad.v:14:34: $fopen mode should be <= 4 characters
-   14 |       file = $fopen("/dev/null", "somereallywidebad");
-      |                                  ^~~~~~~~~~~~~~~~~~~
-        ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
-%Error: Exiting due to
diff --git a/test_regress/t/t_sys_fopen_bad.py b/test_regress/t/t_sys_fopen_bad.py
deleted file mode 100755
index e33e10acf..000000000
--- a/test_regress/t/t_sys_fopen_bad.py
+++ /dev/null
@@ -1,16 +0,0 @@
-#!/usr/bin/env python3
-# DESCRIPTION: Verilator: Verilog Test driver/expect definition
-#
-# Copyright 2024 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
-
-import vltest_bootstrap
-
-test.scenarios('vlt')
-
-test.lint(fails=True, expect_filename=test.golden_filename)
-
-test.passes()
diff --git a/test_regress/t/t_sys_fopen_bad.v b/test_regress/t/t_sys_fopen_bad.v
deleted file mode 100644
index 9d633d4fe..000000000
--- a/test_regress/t/t_sys_fopen_bad.v
+++ /dev/null
@@ -1,17 +0,0 @@
-// DESCRIPTION: Verilator: Verilog Test module
-//
-// Copyright 2022 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
-
-module t ();
-
-   integer file;
-
-   initial begin
-      file = $fopen("/dev/null", "somereallywidebad");
-   end
-
-endmodule