diff --git a/core/src/main/java/jef/asm/AsmParser.java b/core/src/main/java/jef/asm/AsmParser.java
index c142362..9f617f8 100644
--- a/core/src/main/java/jef/asm/AsmParser.java
+++ b/core/src/main/java/jef/asm/AsmParser.java
@@ -2,6 +2,7 @@ package jef.asm;
 
 import jef.serializable.SerializableFunction;
 import jef.serializable.SerializablePredicate;
+import jef.util.Check;
 import lombok.Getter;
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.Opcodes;
@@ -18,18 +19,18 @@ public class AsmParser {
     private final Method method;
 
     public AsmParser(SerializablePredicate<?> predicate) {
-        this.lambda = predicate;
+        this.lambda = Check.notNull(predicate, "predicate");
         this.method = null;
     }
 
     public AsmParser(SerializableFunction<?, ?> function) {
-        this.lambda = function;
+        this.lambda = Check.notNull(function, "function");
         this.method = null;
     }
 
     public AsmParser(Method method) {
         this.lambda = null;
-        this.method = method;
+        this.method = Check.notNull(method, "method");
     }
 
     public AsmParseResult parse() throws AsmParseException {
@@ -39,7 +40,7 @@ public class AsmParser {
             } else if (this.method != null) {
                 return parseMethodExpression();
             }
-            throw new IllegalStateException();
+            throw new IllegalStateException("Illegal state");
         } catch (Exception e) {
             throw new AsmParseException("PredicateParser: failed to parse expression: " + e.getLocalizedMessage(), e);
         }
@@ -58,11 +59,7 @@ public class AsmParser {
         cls = Class.forName(classname.replace("/", "."));
         var is = loader.getResourceAsStream(cls.getName().replace(".", "/") + ".class");
 
-        var cr = new ClassReader(is);
-        var visiter = new FilterClassVisitor(Opcodes.ASM9, lambdaname, args);
-        cr.accept(visiter, 0);
-
-        return visiter.getResult();
+        return parseCommon(is, lambdaname, args);
     }
 
     private AsmParseResult parseMethodExpression() throws Exception {