diff --git a/Changes b/Changes
index 5120975d3..4e1f71fe7 100644
--- a/Changes
+++ b/Changes
@@ -18,6 +18,7 @@ Verilator 5.037 devel
 * Support assignments to concatenations with impure RHS (#6002). [Ryszard Rozak, Antmicro Ltd.]
 * Support SARIF JSON diagnostic output with `--diagnostics-sarif`. (#6017)
 * Support 1-bit params with -G and -pvalue (#6051) (#6082). [Paul Swirhun]
+* Support `$timeformat` with missing arguments (#6113). [Alex Solomatnikov]
 * Support parameter forward types.
 * Add PROCINITASSIGN on initial assignments to process variables (#2481). [Niraj Menon]
 * Add BADVLTPRAGMA on unknown Verilator pragmas (#5945). [Shou-Li Hsu]
diff --git a/include/verilated.cpp b/include/verilated.cpp
index a1e6975a0..eb59da7fa 100644
--- a/include/verilated.cpp
+++ b/include/verilated.cpp
@@ -2567,12 +2567,13 @@ void VL_PRINTTIMESCALE(const char* namep, const char* timeunitp,
     VL_PRINTF_MT("Time scale of %s is %s / %s\n", namep, timeunitp,
                  contextp->timeprecisionString());
 }
-void VL_TIMEFORMAT_IINI(int units, int precision, const std::string& suffix, int width,
+void VL_TIMEFORMAT_IINI(bool hasUnits, int units, bool hasPrecision, int precision, bool hasSuffix,
+                        const std::string& suffix, bool hasWidth, int width,
                         VerilatedContext* contextp) VL_MT_SAFE {
-    contextp->impp()->timeFormatUnits(units);
-    contextp->impp()->timeFormatPrecision(precision);
-    contextp->impp()->timeFormatSuffix(suffix);
-    contextp->impp()->timeFormatWidth(width);
+    if (hasUnits) contextp->impp()->timeFormatUnits(units);
+    if (hasPrecision) contextp->impp()->timeFormatPrecision(precision);
+    if (hasSuffix) contextp->impp()->timeFormatSuffix(suffix);
+    if (hasWidth) contextp->impp()->timeFormatWidth(width);
 }
 
 //======================================================================
diff --git a/include/verilated_funcs.h b/include/verilated_funcs.h
index e62e9f172..03b3ed685 100644
--- a/include/verilated_funcs.h
+++ b/include/verilated_funcs.h
@@ -2800,7 +2800,8 @@ extern IData VL_SSCANF_INNX(int lbits, const std::string& ld, const std::string&
 extern void VL_SFORMAT_NX(int obits_ignored, std::string& output, const std::string& format,
                           int argc, ...) VL_MT_SAFE;
 extern std::string VL_SFORMATF_N_NX(const std::string& format, int argc, ...) VL_MT_SAFE;
-extern void VL_TIMEFORMAT_IINI(int units, int precision, const std::string& suffix, int width,
+extern void VL_TIMEFORMAT_IINI(bool hasUnits, int units, bool hasPrecision, int precision,
+                               bool hasSuffix, const std::string& suffix, bool hasWidth, int width,
                                VerilatedContext* contextp) VL_MT_SAFE;
 extern IData VL_VALUEPLUSARGS_INW(int rbits, const std::string& ld, WDataOutP rwp) VL_MT_SAFE;
 inline IData VL_VALUEPLUSARGS_INI(int rbits, const std::string& ld, CData& rdr) VL_MT_SAFE {
diff --git a/src/V3AstNodeOther.h b/src/V3AstNodeOther.h
index af08c34e6..6dfe7d32e 100644
--- a/src/V3AstNodeOther.h
+++ b/src/V3AstNodeOther.h
@@ -3490,10 +3490,10 @@ public:
 };
 class AstTimeFormat final : public AstNodeStmt {
     // Parents: stmtlist
-    // @astgen op1 := unitsp : AstNodeExpr
-    // @astgen op2 := precisionp : AstNodeExpr
-    // @astgen op3 := suffixp : AstNodeExpr
-    // @astgen op4 := widthp : AstNodeExpr
+    // @astgen op1 := unitsp : Optional[AstNodeExpr]
+    // @astgen op2 := precisionp : Optional[AstNodeExpr]
+    // @astgen op3 := suffixp : Optional[AstNodeExpr]
+    // @astgen op4 := widthp : Optional[AstNodeExpr]
 public:
     AstTimeFormat(FileLine* fl, AstNodeExpr* unitsp, AstNodeExpr* precisionp, AstNodeExpr* suffixp,
                   AstNodeExpr* widthp)
diff --git a/src/V3EmitCFunc.h b/src/V3EmitCFunc.h
index 99cc3a259..a5bc9f002 100644
--- a/src/V3EmitCFunc.h
+++ b/src/V3EmitCFunc.h
@@ -1083,13 +1083,33 @@ public:
     }
     void visit(AstTimeFormat* nodep) override {
         putns(nodep, "VL_TIMEFORMAT_IINI(");
-        iterateAndNextConstNull(nodep->unitsp());
+        if (nodep->unitsp()) {
+            puts("true, ");
+            iterateAndNextConstNull(nodep->unitsp());
+        } else {
+            puts("false, 0");
+        }
         puts(", ");
-        iterateAndNextConstNull(nodep->precisionp());
+        if (nodep->precisionp()) {
+            puts("true, ");
+            iterateAndNextConstNull(nodep->precisionp());
+        } else {
+            puts("false, 0");
+        }
         puts(", ");
-        emitCvtPackStr(nodep->suffixp());
+        if (nodep->suffixp()) {
+            puts("true, ");
+            emitCvtPackStr(nodep->suffixp());
+        } else {
+            puts("false, \"\"");
+        }
         puts(", ");
-        iterateAndNextConstNull(nodep->widthp());
+        if (nodep->widthp()) {
+            puts("true, ");
+            iterateAndNextConstNull(nodep->widthp());
+        } else {
+            puts("false, 0");
+        }
         puts(", vlSymsp->_vm_contextp__);\n");
     }
     void visit(AstTimePrecision* nodep) override {
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index 048480fb9..aa4fff739 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -5718,10 +5718,11 @@ class WidthVisitor final : public VNVisitor {
     }
     void visit(AstTimeFormat* nodep) override {
         assertAtStatement(nodep);
-        iterateCheckSigned32(nodep, "units", nodep->unitsp(), BOTH);
-        iterateCheckSigned32(nodep, "precision", nodep->precisionp(), BOTH);
-        iterateCheckString(nodep, "suffix", nodep->suffixp(), BOTH);
-        iterateCheckSigned32(nodep, "width", nodep->widthp(), BOTH);
+        if (nodep->unitsp()) iterateCheckSigned32(nodep, "units", nodep->unitsp(), BOTH);
+        if (nodep->precisionp())
+            iterateCheckSigned32(nodep, "precision", nodep->precisionp(), BOTH);
+        if (nodep->suffixp()) iterateCheckString(nodep, "suffix", nodep->suffixp(), BOTH);
+        if (nodep->widthp()) iterateCheckSigned32(nodep, "width", nodep->widthp(), BOTH);
     }
     void visit(AstUCStmt* nodep) override {
         // Just let all arguments seek their natural sizes
diff --git a/src/verilog.y b/src/verilog.y
index 3e4ed1251..fc3dc5224 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -4362,8 +4362,14 @@ system_t_call<nodeStmtp>:       // IEEE: system_tf_call (as task)
         |       yD_PRINTTIMESCALE                       { $$ = new AstPrintTimeScale{$1}; }
         |       yD_PRINTTIMESCALE '(' ')'               { $$ = new AstPrintTimeScale{$1}; }
         |       yD_PRINTTIMESCALE '(' idClassSel ')'    { $$ = new AstPrintTimeScale{$1}; DEL($3); }
-        |       yD_TIMEFORMAT '(' expr ',' expr ',' expr ',' expr ')'
+        |       yD_TIMEFORMAT '(' exprE ',' exprE ',' exprE ',' exprE ')'
                         { $$ = new AstTimeFormat{$1, $3, $5, $7, $9}; }
+        |       yD_TIMEFORMAT '(' exprE ',' exprE ',' exprE ')'
+                        { $$ = new AstTimeFormat{$1, $3, $5, $7, nullptr}; }
+        |       yD_TIMEFORMAT '(' exprE ',' exprE ')'
+                        { $$ = new AstTimeFormat{$1, $3, $5, nullptr, nullptr}; }
+        |       yD_TIMEFORMAT '(' exprE ')'
+                        { $$ = new AstTimeFormat{$1, $3, nullptr, nullptr, nullptr}; }
         //
         |       yD_READMEMB '(' expr ',' idClassSel ')'                         { $$ = new AstReadMem{$1, false, $3, $5, nullptr, nullptr}; }
         |       yD_READMEMB '(' expr ',' idClassSel ',' expr ')'                { $$ = new AstReadMem{$1, false, $3, $5, $7, nullptr}; }
diff --git a/test_regress/t/t_display_time.out b/test_regress/t/t_display_time.out
index 9f28e2cd5..93b8a3cb5 100644
--- a/test_regress/t/t_display_time.out
+++ b/test_regress/t/t_display_time.out
@@ -3,5 +3,10 @@ default:   [10] 0t time [                  10] No0 time  p=                  10
 -9,0,,10:  [10] 0t time [        10] No0 time  p=                  10 0p='ha
 -9,0,ns,5: [10ns] 0t time [ 10ns] No0 time  p=                  10 0p='ha
 -9,3,ns,8: [10.000ns] 0t time [10.000ns] No0 time  p=                  10 0p='ha
+-9,3,ns  : [10.000ns] 0t time [10.000ns] No0 time  p=                  10 0p='ha
+-9,3:      [10.000ns] 0t time [10.000ns] No0 time  p=                  10 0p='ha
+-9:        [10.000ns] 0t time [10.000ns] No0 time  p=                  10 0p='ha
+:          [10.000ns] 0t time [10.000ns] No0 time  p=                  10 0p='ha
+-9,,,:     [10.000ns] 0t time [10.000ns] No0 time  p=                  10 0p='ha
 
 *-* All Finished *-*
diff --git a/test_regress/t/t_display_time.v b/test_regress/t/t_display_time.v
index 72b84a94c..f5d4c75da 100644
--- a/test_regress/t/t_display_time.v
+++ b/test_regress/t/t_display_time.v
@@ -30,6 +30,21 @@ module t (/*AUTOARG*/
          $timeformat(-9, 3, "ns", 8);
          $write("-9,3,ns,8: [%0t] 0t time [%t] No0 time  p=%p 0p=%0p\n",
                 $time, $time, $time, $time);
+         $timeformat(-9, 3, "ns");
+         $write("-9,3,ns  : [%0t] 0t time [%t] No0 time  p=%p 0p=%0p\n",
+                $time, $time, $time, $time);
+         $timeformat(-9, 3);
+         $write("-9,3:      [%0t] 0t time [%t] No0 time  p=%p 0p=%0p\n",
+                $time, $time, $time, $time);
+         $timeformat(-9);
+         $write("-9:        [%0t] 0t time [%t] No0 time  p=%p 0p=%0p\n",
+                $time, $time, $time, $time);
+         $timeformat();
+         $write(":          [%0t] 0t time [%t] No0 time  p=%p 0p=%0p\n",
+                $time, $time, $time, $time);
+         $timeformat(-9,,,);
+         $write("-9,,,:     [%0t] 0t time [%t] No0 time  p=%p 0p=%0p\n",
+                $time, $time, $time, $time);
          $write("\n");
          $write("*-* All Finished *-*\n");
          $finish;