diff --git a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/CJMP.java b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/CJMP.java
index 4941e28..cf09e1f 100644
--- a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/CJMP.java
+++ b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/CJMP.java
@@ -1,5 +1,6 @@
 package org.teachfx.antlr4.ep20.ir.stmt;
 
+import org.jetbrains.annotations.NotNull;
 import org.teachfx.antlr4.ep20.ir.IRVisitor;
 import org.teachfx.antlr4.ep20.ir.JMPInstr;
 import org.teachfx.antlr4.ep20.ir.expr.VarSlot;
@@ -11,7 +12,7 @@ public class CJMP extends Stmt implements JMPInstr {
     private LinearIRBlock elseBlock;
 
 
-    public CJMP(VarSlot cond, LinearIRBlock thenLabel, LinearIRBlock elseLabel) {
+    public CJMP(@NotNull VarSlot cond, @NotNull LinearIRBlock thenLabel,@NotNull LinearIRBlock elseLabel) {
         this.cond = cond;
         this.thenBlock = thenLabel;
         this.elseBlock = elseLabel;
diff --git a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/JMP.java b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/JMP.java
index b489f57..9990697 100644
--- a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/JMP.java
+++ b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/JMP.java
@@ -1,5 +1,6 @@
 package org.teachfx.antlr4.ep20.ir.stmt;
 
+import org.jetbrains.annotations.NotNull;
 import org.teachfx.antlr4.ep20.ir.IRVisitor;
 import org.teachfx.antlr4.ep20.ir.JMPInstr;
 import org.teachfx.antlr4.ep20.pass.cfg.LinearIRBlock;
@@ -11,7 +12,7 @@ public <S, E> S accept(IRVisitor<S, E> visitor) {
         return visitor.visit(this);
     }
 
-    public JMP(LinearIRBlock block)
+    public JMP(@NotNull LinearIRBlock block)
     {
         this.next = block;
         block.refJMP(this);