diff --git a/src/ui.ts b/src/ui.ts
index 45fe704..30657d5 100644
--- a/src/ui.ts
+++ b/src/ui.ts
@@ -18,11 +18,11 @@ function menuRun(): void {
 function menuClear(): void {
   SpreadsheetApp.getActiveSpreadsheet()
     .getSheetByName("Run")
-    .getRange("A3:H")
+    .getRange("A3:F")
     .clearContent();
   SpreadsheetApp.getActiveSpreadsheet()
     .getSheetByName("Run")
-    .getRange("D2:H2")
+    .getRange("D2:F")
     .clearContent();
   SpreadsheetApp.getActiveSpreadsheet()
     .getSheetByName("Run")
diff --git a/src/vm.ts b/src/vm.ts
index 1628ad4..1d48f3d 100644
--- a/src/vm.ts
+++ b/src/vm.ts
@@ -141,12 +141,32 @@ function step(n: number = 0): void {
   // opcode(dst, res)
   switch (instruction.Opcode) {
     case Opcodes.Call:
-      runSheet
-        .getRange(op0Addr)
-        .setValue(registers[Registers.PC] + size(instruction));
-      runSheet.getRange(dstAddr).setValue(registers[Registers.FP]);
+      let validCallOp0Value: number | string =
+        registers[Registers.PC] + size(instruction);
+      let validCallDstValue: number | string = registers[Registers.FP];
+      if (op0Value == "") {
+        runSheet.getRange(op0Addr).setValue(validCallOp0Value);
+      }
+      if (dstValue == "") {
+        runSheet.getRange(dstAddr).setValue(validCallDstValue);
+      }
+      op0Value =
+        instruction.Op0Register === Registers.PC
+          ? op0Addr
+          : runSheet.getRange(op0Addr).getValue();
+      dstValue =
+        instruction.DstRegister === Registers.PC
+          ? dstAddr
+          : runSheet.getRange(dstAddr).getValue();
+      if (
+        Number(dstValue) !== Number(validCallDstValue) ||
+        Number(op0Value) !== Number(validCallOp0Value)
+      ) {
+        throw new AssertEqError();
+      }
       break;
     case Opcodes.AssertEq:
+      let validAssertEqDstValue: number | string;
       switch (instruction.ResLogic) {
         case ResLogics.Add:
           if (op0Value === "") {
@@ -164,6 +184,7 @@ function step(n: number = 0): void {
               .getRange(dstAddr)
               .setValue(BigInt(op0Value) + BigInt(op1Value));
           }
+          validAssertEqDstValue = Number(BigInt(op0Value) + BigInt(op1Value));
           break;
         case ResLogics.Mul:
           if (op0Value === "") {
@@ -181,6 +202,7 @@ function step(n: number = 0): void {
               .getRange(dstAddr)
               .setValue(BigInt(op0Value) * BigInt(op1Value));
           }
+          validAssertEqDstValue = Number(BigInt(op0Value) * BigInt(op1Value));
           break;
         case ResLogics.Op1:
           if (op1Value === "") {
@@ -189,8 +211,17 @@ function step(n: number = 0): void {
           if (dstValue === "") {
             runSheet.getRange(dstAddr).setValue(BigInt(op1Value));
           }
+          validAssertEqDstValue = Number(BigInt(op1Value));
           break;
       }
+      dstValue =
+        instruction.DstRegister === Registers.PC
+          ? dstAddr
+          : runSheet.getRange(dstAddr).getValue();
+      if (Number(dstValue) !== Number(validAssertEqDstValue)) {
+        throw new AssertEqError();
+      }
+      break;
   }
 
   op0Value =