diff --git a/include/verilated.cpp b/include/verilated.cpp
index b38855679..e765dff9a 100644
--- a/include/verilated.cpp
+++ b/include/verilated.cpp
@@ -2367,7 +2367,7 @@ static void removeCb(Verilated::VoidPCb cb, void* datap, VoidPCbList& cbs) {
     std::pair<Verilated::VoidPCb, void*> pair(cb, datap);
     cbs.remove(pair);
 }
-static void runCallbacks(VoidPCbList& cbs) VL_MT_SAFE {
+static void runCallbacks(const VoidPCbList& cbs) VL_MT_SAFE {
     for (const auto& i : cbs) i.first(i.second);
 }
 
diff --git a/include/verilated_imp.h b/include/verilated_imp.h
index 2a54a221c..73933a1f3 100644
--- a/include/verilated_imp.h
+++ b/include/verilated_imp.h
@@ -61,7 +61,7 @@ private:
     std::function<void()> m_cb;  ///< Lambda to execute when message received
 public:
     // CONSTRUCTORS
-    VerilatedMsg(const std::function<void()>& cb)
+    explicit VerilatedMsg(const std::function<void()>& cb)
         : m_mtaskId{Verilated::mtaskId()}
         , m_cb{cb} {}
     ~VerilatedMsg() = default;
diff --git a/include/verilated_sym_props.h b/include/verilated_sym_props.h
index 5cbe877aa..175fe93f3 100644
--- a/include/verilated_sym_props.h
+++ b/include/verilated_sym_props.h
@@ -81,9 +81,9 @@ class VerilatedVarProps VL_NOT_FINAL {
     std::vector<VerilatedRange> m_unpacked;  // Unpacked array ranges
     void initUnpacked(const int* ulims) {
         for (int i = 0; i < m_udims; ++i) {
-            const int left = ulims ? ulims[2 * i + 0] : 0;
-            const int right = ulims ? ulims[2 * i + 1] : 0;
-            m_unpacked.emplace_back(left, right);
+            const int uleft = ulims ? ulims[2 * i + 0] : 0;
+            const int uright = ulims ? ulims[2 * i + 1] : 0;
+            m_unpacked.emplace_back(uleft, uright);
         }
     }
     // CONSTRUCTORS
diff --git a/include/verilated_vpi.cpp b/include/verilated_vpi.cpp
index 3ea2afa39..4cbaebd04 100644
--- a/include/verilated_vpi.cpp
+++ b/include/verilated_vpi.cpp
@@ -272,7 +272,7 @@ public:
         m_entSize = varp->entSize();
         m_varDatap = varp->datap();
     }
-    VerilatedVpioVar(const VerilatedVpioVar* varp) {
+    explicit VerilatedVpioVar(const VerilatedVpioVar* varp) {
         if (varp) {
             m_varp = varp->m_varp;
             m_scopep = varp->m_scopep;
diff --git a/src/V3Ast.cpp b/src/V3Ast.cpp
index 9e2b9843b..94ef386f9 100644
--- a/src/V3Ast.cpp
+++ b/src/V3Ast.cpp
@@ -130,7 +130,6 @@ string AstNode::encodeName(const string& namein) {
     // Then we also won't need to save the table of hased values
     VName vname{out};
     return vname.hashedName();
-    return out;
 }
 
 string AstNode::encodeNumber(vlsint64_t num) {
diff --git a/src/V3AstNodes.cpp b/src/V3AstNodes.cpp
index dbd2a8716..4ce5bb2b9 100644
--- a/src/V3AstNodes.cpp
+++ b/src/V3AstNodes.cpp
@@ -727,11 +727,13 @@ AstNodeDType* AstNodeDType::dtypeDimensionp(int dimension) {
         } else if (AstBasicDType* adtypep = VN_CAST(dtypep, BasicDType)) {
             // AstBasicDType - nothing below, return null
             if (adtypep->isRanged()) {
+                // cppcheck-suppress unreadVariable  // Cppcheck bug - thinks dim isn't used
                 if ((dim++) == dimension) return adtypep;
             }
             return nullptr;
         } else if (AstNodeUOrStructDType* adtypep = VN_CAST(dtypep, NodeUOrStructDType)) {
             if (adtypep->packed()) {
+                // cppcheck-suppress unreadVariable  // Cppcheck bug - thinks dim isn't used
                 if ((dim++) == dimension) return adtypep;
             }
             return nullptr;
diff --git a/src/V3AstNodes.h b/src/V3AstNodes.h
index 20c418bd7..94cc8a8e2 100644
--- a/src/V3AstNodes.h
+++ b/src/V3AstNodes.h
@@ -1976,6 +1976,7 @@ private:
         m_attrSFormat = false;
         m_attrSplitVar = false;
         m_fileDescr = false;
+        m_isRand = false;
         m_isConst = false;
         m_isStatic = false;
         m_isPulldown = false;
@@ -4588,7 +4589,7 @@ public:
 class AstDisableFork final : public AstNodeStmt {
     // A "disable fork" statement
 public:
-    AstDisableFork(FileLine* fl)
+    explicit AstDisableFork(FileLine* fl)
         : ASTGEN_SUPER(fl) {}
     ASTNODE_NODE_FUNCS(DisableFork)
 };
@@ -4596,7 +4597,7 @@ public:
 class AstWaitFork final : public AstNodeStmt {
     // A "wait fork" statement
 public:
-    AstWaitFork(FileLine* fl)
+    explicit AstWaitFork(FileLine* fl)
         : ASTGEN_SUPER(fl) {}
     ASTNODE_NODE_FUNCS(WaitFork)
 };
@@ -4649,7 +4650,7 @@ class AstJumpBlock final : public AstNodeStmt {
     // Parents:  {statement list}
     // Children: {statement list, with JumpGo and JumpLabel below}
 private:
-    AstJumpLabel* m_labelp;  // [After V3Jump] Pointer to declaration
+    AstJumpLabel* m_labelp = nullptr;  // [After V3Jump] Pointer to declaration
     int m_labelNum = 0;  // Set by V3EmitCSyms to tell final V3Emit what to increment
 public:
     // After construction must call ->labelp to associate with appropriate label
@@ -4835,7 +4836,7 @@ class AstConsDynArray final : public AstNodeMath {
     // Parents: math
     // Children: expression (elements or other queues)
 public:
-    AstConsDynArray(FileLine* fl, AstNode* lhsp = nullptr, AstNode* rhsp = nullptr)
+    explicit AstConsDynArray(FileLine* fl, AstNode* lhsp = nullptr, AstNode* rhsp = nullptr)
         : ASTGEN_SUPER(fl) {
         setNOp1p(lhsp);
         setNOp2p(rhsp);
@@ -4857,7 +4858,7 @@ class AstConsQueue final : public AstNodeMath {
     // Parents: math
     // Children: expression (elements or other queues)
 public:
-    AstConsQueue(FileLine* fl, AstNode* lhsp = nullptr, AstNode* rhsp = nullptr)
+    explicit AstConsQueue(FileLine* fl, AstNode* lhsp = nullptr, AstNode* rhsp = nullptr)
         : ASTGEN_SUPER(fl) {
         setNOp1p(lhsp);
         setNOp2p(rhsp);
@@ -5121,7 +5122,7 @@ class AstPrintTimeScale final : public AstNodeStmt {
     string m_name;  // Parent module name
     VTimescale m_timeunit;  // Parent module time unit
 public:
-    AstPrintTimeScale(FileLine* fl)
+    explicit AstPrintTimeScale(FileLine* fl)
         : ASTGEN_SUPER(fl) {}
     ASTNODE_NODE_FUNCS(PrintTimeScale)
     virtual void name(const string& name) override { m_name = name; }
diff --git a/src/V3Combine.cpp b/src/V3Combine.cpp
index 6659b2f54..70fcb18a6 100644
--- a/src/V3Combine.cpp
+++ b/src/V3Combine.cpp
@@ -224,6 +224,7 @@ private:
                 AstNode* node1p = it->second;
                 AstCFunc* cfunc1p = VN_CAST(node1p, CFunc);
                 if (!cfunc1p) continue;
+                // cppcheck-suppress compareBoolExpressionWithInt
                 if (cfunc1p->slow() != slow) continue;
                 V3Hash hashval = it->first;
                 UASSERT_OBJ(!hashval.isIllegal(), node1p, "Illegal (unhashed) nodes");
diff --git a/src/V3EmitMk.cpp b/src/V3EmitMk.cpp
index cf50f1ea2..42621c812 100644
--- a/src/V3EmitMk.cpp
+++ b/src/V3EmitMk.cpp
@@ -311,9 +311,6 @@ class EmitMkHierVerilation final {
         }
         of.puts("\n");
     }
-    void emitOpts(V3OutMkFile& of, const V3StringList& opts) const {
-        for (const string& i : opts) { of.puts("\t\t" + i + " \\\n"); }
-    }
     void emitLaunchVerilator(V3OutMkFile& of, const string& argsFile) const {
         of.puts("\t@$(MAKE) -C $(VM_HIER_RUN_DIR) -f " + m_makefile
                 + " hier_launch_verilator \\\n");
@@ -420,5 +417,5 @@ void V3EmitMk::emitmk() {
 
 void V3EmitMk::emitHierVerilation(const V3HierBlockPlan* planp) {
     UINFO(2, __FUNCTION__ << ": " << endl);
-    EmitMkHierVerilation emitter(planp);
+    EmitMkHierVerilation{planp};
 }
diff --git a/src/V3File.cpp b/src/V3File.cpp
index 53d446d05..94a363508 100644
--- a/src/V3File.cpp
+++ b/src/V3File.cpp
@@ -584,12 +584,12 @@ protected:
         }
         return true;
     }
-    static size_t listSize(StrList& sl) {
+    static size_t listSize(const StrList& sl) {
         size_t out = 0;
         for (const string& i : sl) out += i.length();
         return out;
     }
-    static string listString(StrList& sl) {
+    static string listString(const StrList& sl) {
         string out;
         for (const string& i : sl) out += i;
         return out;
diff --git a/src/V3Global.h b/src/V3Global.h
index d7d17c760..d25cae1bc 100644
--- a/src/V3Global.h
+++ b/src/V3Global.h
@@ -52,7 +52,7 @@ template <typename T> class VRestorer {
     const T m_saved;  // Value saved, for later restore
 
 public:
-    VRestorer(T& permr)
+    explicit VRestorer(T& permr)
         : m_ref(permr)
         , m_saved(permr) {}
     ~VRestorer() { m_ref = m_saved; }
diff --git a/src/V3HierBlock.cpp b/src/V3HierBlock.cpp
index c18554c12..0e27f4da1 100644
--- a/src/V3HierBlock.cpp
+++ b/src/V3HierBlock.cpp
@@ -344,7 +344,7 @@ void V3HierBlockPlan::createPlan(AstNetlist* nodep) {
     }
 
     std::unique_ptr<V3HierBlockPlan> planp(new V3HierBlockPlan());
-    { HierBlockUsageCollectVisitor visitor(planp.get(), nodep); }
+    { HierBlockUsageCollectVisitor{planp.get(), nodep}; }
 
     V3Stats::addStat("HierBlock, Hierarchical blocks", planp->m_blocks.size());
 
diff --git a/src/V3LinkDot.cpp b/src/V3LinkDot.cpp
index a8b6616ff..38ddb93d4 100644
--- a/src/V3LinkDot.cpp
+++ b/src/V3LinkDot.cpp
@@ -1283,9 +1283,9 @@ class LinkDotFindVisitor final : public AstNVisitor {
             VL_DO_DANGLING(argp->unlinkFrBackWithNext()->deleteTree(), argp);
         }
         // Type depends on the method used, let V3Width figure it out later
-        const auto indexArgRefp = new AstLambdaArgRef(argFl, name + "__DOT__index", true);
-        const auto valueArgRefp = new AstLambdaArgRef(argFl, name, false);
         if (nodep->exprp()) {  // Else empty expression and pretend no "with"
+            const auto indexArgRefp = new AstLambdaArgRef(argFl, name + "__DOT__index", true);
+            const auto valueArgRefp = new AstLambdaArgRef(argFl, name, false);
             const auto newp = new AstWith(nodep->fileline(), indexArgRefp, valueArgRefp,
                                           nodep->exprp()->unlinkFrBackWithNext());
             funcrefp->addPinsp(newp);
@@ -2087,9 +2087,9 @@ private:
                     } else {
                         auto cextp = VN_CAST(classp->extendsp(), ClassExtends);
                         UASSERT_OBJ(cextp, nodep, "Bad super extends link");
-                        auto classp = cextp->classp();
-                        UASSERT_OBJ(classp, nodep, "Bad superclass");
-                        m_ds.m_dotSymp = m_statep->getNodeSym(classp);
+                        auto sclassp = cextp->classp();
+                        UASSERT_OBJ(sclassp, nodep, "Bad superclass");
+                        m_ds.m_dotSymp = m_statep->getNodeSym(sclassp);
                         UINFO(8, "     super. " << m_ds.ascii() << endl);
                     }
                 }
diff --git a/src/V3Number.cpp b/src/V3Number.cpp
index adacecbc9..96aa7d185 100644
--- a/src/V3Number.cpp
+++ b/src/V3Number.cpp
@@ -516,7 +516,8 @@ string V3Number::ascii(bool prefixed, bool cleanVerilog) const {
 
     bool binary = (isFourState()
 #ifdef V3NUMBER_ASCII_BINARY
-                   || 1
+                   // cppcheck-suppress konwnConditionTrueFalse
+                   || true
 #endif
     );
     // out<<"-"<<hex<<m_value[0]<<"-";
diff --git a/src/V3Param.cpp b/src/V3Param.cpp
index 00fad3e4d..cc81316ae 100644
--- a/src/V3Param.cpp
+++ b/src/V3Param.cpp
@@ -722,7 +722,7 @@ public:
     }
 
     // CONSTRUCTORS
-    ParamProcessor(AstNetlist* nodep)
+    explicit ParamProcessor(AstNetlist* nodep)
         : m_hierBlocks{v3Global.opt.hierBlocks(), nodep} {
         for (AstNodeModule* modp = nodep->modulesp(); modp;
              modp = VN_CAST(modp->nextp(), NodeModule)) {
diff --git a/src/V3PreProc.cpp b/src/V3PreProc.cpp
index b18dd84c8..5bddbe54a 100644
--- a/src/V3PreProc.cpp
+++ b/src/V3PreProc.cpp
@@ -1317,7 +1317,6 @@ int V3PreProcImp::getStateToken() {
                 // Convert any newlines to spaces, so we don't get a
                 // multiline "..." without \ escapes.
                 // The spec is silent about this either way; simulators vary
-                string::size_type pos;
                 std::replace(out.begin(), out.end(), '\n', ' ');
                 unputString(string("\"") + out + "\"");
                 statePop();
diff --git a/src/V3Randomize.cpp b/src/V3Randomize.cpp
index d1bbf3c51..25abd6630 100644
--- a/src/V3Randomize.cpp
+++ b/src/V3Randomize.cpp
@@ -54,10 +54,10 @@ private:
                 // If member is rand and of class type, mark its class
                 if (VN_IS(memberp, Var) && VN_CAST(memberp, Var)->isRand()) {
                     if (auto* classRefp = VN_CAST(memberp->dtypep(), ClassRefDType)) {
-                        auto* classp = classRefp->classp();
-                        markMembers(classp);
-                        markDerived(classp);
-                        classRefp->classp()->user1(true);
+                        auto* rclassp = classRefp->classp();
+                        markMembers(rclassp);
+                        markDerived(rclassp);
+                        rclassp->user1(true);
                     }
                 }
             }
@@ -158,10 +158,10 @@ private:
                       StructDType)) {
             AstNodeStmt* stmtsp = nullptr;
             offset += memberp ? memberp->lsb() : 0;
-            for (auto* memberp = structDtp->membersp(); memberp;
-                 memberp = VN_CAST(memberp->nextp(), MemberDType)) {
+            for (auto* smemberp = structDtp->membersp(); smemberp;
+                 smemberp = VN_CAST(smemberp->nextp(), MemberDType)) {
                 auto* randp = newRandStmtsp(fl, stmtsp ? varrefp->cloneTree(false) : varrefp,
-                                            offset, memberp);
+                                            offset, smemberp);
                 if (stmtsp) {
                     stmtsp->addNext(randp);
                 } else {
diff --git a/src/V3Undriven.cpp b/src/V3Undriven.cpp
index 5bf4348ac..fcdad754d 100644
--- a/src/V3Undriven.cpp
+++ b/src/V3Undriven.cpp
@@ -411,8 +411,8 @@ private:
         VL_RESTORER(m_alwaysCombp);
         {
             AstNode::user2ClearTree();
-            if (nodep->keyword() == VAlwaysKwd::ALWAYS_COMB) UINFO(9, "   " << nodep << endl);
             if (nodep->keyword() == VAlwaysKwd::ALWAYS_COMB) {
+                UINFO(9, "   " << nodep << endl);
                 m_alwaysCombp = nodep;
             } else {
                 m_alwaysCombp = nullptr;
diff --git a/src/verilog.y b/src/verilog.y
index 2dfacd20d..81f7d0686 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -288,10 +288,7 @@ static void UNSUPREAL(FileLine* fileline) {
 
 //======================================================================
 
-void yyerror(const char* errmsg) {
-    PARSEP->bisonLastFileline()->v3error(errmsg);
-    static const char* const colonmsg = "syntax error, unexpected";
-}
+void yyerror(const char* errmsg) { PARSEP->bisonLastFileline()->v3error(errmsg); }
 
 void yyerrorf(const char* format, ...) {
     const int maxlen = 2000;