diff --git a/src/de/inetsoftware/jwebassembly/module/WasmBlockInstruction.java b/src/de/inetsoftware/jwebassembly/module/WasmBlockInstruction.java
index e2cde5d..86dd63c 100644
--- a/src/de/inetsoftware/jwebassembly/module/WasmBlockInstruction.java
+++ b/src/de/inetsoftware/jwebassembly/module/WasmBlockInstruction.java
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018 - 2021 Volker Berlin (i-net software)
+   Copyright 2018 - 2022 Volker Berlin (i-net software)
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
@@ -103,6 +103,7 @@ class WasmBlockInstruction extends WasmInstruction {
     AnyType getPushValueType() {
         switch( op ) {
             case IF:
+            case BLOCK:
                 return data != ValueType.empty ? (AnyType)data : null;
             case RETURN:
                 return (AnyType)data;
@@ -151,4 +152,12 @@ class WasmBlockInstruction extends WasmInstruction {
                 return null;
         }
     }
+
+    /**
+     * Only used for debugging
+     */
+    @Override
+    public String toString() {
+        return getClass().getSimpleName() + ": " + op + (data == null || data == ValueType.empty ? "" : " " + data);
+    }
 }
diff --git a/src/de/inetsoftware/jwebassembly/module/WasmConstInstruction.java b/src/de/inetsoftware/jwebassembly/module/WasmConstInstruction.java
index 68513c1..b2a146d 100644
--- a/src/de/inetsoftware/jwebassembly/module/WasmConstInstruction.java
+++ b/src/de/inetsoftware/jwebassembly/module/WasmConstInstruction.java
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018 - 2021 Volker Berlin (i-net software)
+   Copyright 2018 - 2022 Volker Berlin (i-net software)
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
@@ -129,4 +129,12 @@ class WasmConstInstruction extends WasmInstruction {
     AnyType[] getPopValueTypes() {
         return null;
     }
+
+    /**
+     * Only used for debugging
+     */
+    @Override
+    public String toString() {
+        return getClass().getSimpleName() + ": " + value;
+    }
 }
diff --git a/src/de/inetsoftware/jwebassembly/module/WasmLocalInstruction.java b/src/de/inetsoftware/jwebassembly/module/WasmLocalInstruction.java
index e1bfa8b..97b46bc 100644
--- a/src/de/inetsoftware/jwebassembly/module/WasmLocalInstruction.java
+++ b/src/de/inetsoftware/jwebassembly/module/WasmLocalInstruction.java
@@ -150,4 +150,12 @@ class WasmLocalInstruction extends WasmInstruction {
     AnyType[] getPopValueTypes() {
         return op == get  ? null : new AnyType[] { localVariables.getValueType( getIndex() ) };
     }
+
+    /**
+     * Only used for debugging
+     */
+    @Override
+    public String toString() {
+        return getClass().getSimpleName() + ": local." + op + ' ' + idx;
+    }
 }
diff --git a/src/de/inetsoftware/jwebassembly/module/WasmNumericInstruction.java b/src/de/inetsoftware/jwebassembly/module/WasmNumericInstruction.java
index 04a951a..be4a6b9 100644
--- a/src/de/inetsoftware/jwebassembly/module/WasmNumericInstruction.java
+++ b/src/de/inetsoftware/jwebassembly/module/WasmNumericInstruction.java
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018 - 2021 Volker Berlin (i-net software)
+   Copyright 2018 - 2022 Volker Berlin (i-net software)
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
@@ -133,4 +133,12 @@ class WasmNumericInstruction extends WasmInstruction {
                 return new AnyType[] { valueType, valueType };
         }
     }
+
+    /**
+     * Only used for debugging
+     */
+    @Override
+    public String toString() {
+        return getClass().getSimpleName() + ": " + valueType + '.' + numOp;
+    }
 }