diff --git a/src/main/java/org/parabot/core/asm/adapters/AddCallbackAdapter.java b/src/main/java/org/parabot/core/asm/adapters/AddCallbackAdapter.java
index 1384452..1b6ea3f 100644
--- a/src/main/java/org/parabot/core/asm/adapters/AddCallbackAdapter.java
+++ b/src/main/java/org/parabot/core/asm/adapters/AddCallbackAdapter.java
@@ -40,17 +40,19 @@ public class AddCallbackAdapter implements Injectable, Opcodes {
         Label        l0     = new Label();
         inject.add(new LabelNode(l0));
         int offset = 0;
-        for (int arg : args) {
-            if (Modifier.isStatic(method.access)) {
-                int loadOpcode = ASMUtils.getLoadOpcode(types[arg]
-                        .getDescriptor());
-                inject.add(new VarInsnNode(loadOpcode, arg + offset));
-                if (loadOpcode == Opcodes.LLOAD) {
-                    offset++;
+        if (args != null && args.length > 0) {
+            for (int arg : args) {
+                if (Modifier.isStatic(method.access)) {
+                    int loadOpcode = ASMUtils.getLoadOpcode(types[arg]
+                            .getDescriptor());
+                    inject.add(new VarInsnNode(loadOpcode, arg + offset));
+                    if (loadOpcode == Opcodes.LLOAD) {
+                        offset++;
+                    }
+                } else {
+                    inject.add(new VarInsnNode(ASMUtils.getLoadOpcode(types[arg]
+                            .getDescriptor()), arg + 1));
                 }
-            } else {
-                inject.add(new VarInsnNode(ASMUtils.getLoadOpcode(types[arg]
-                        .getDescriptor()), arg + 1));
             }
         }
         inject.add(new MethodInsnNode(INVOKESTATIC,
diff --git a/src/main/java/org/parabot/core/asm/wrappers/Callback.java b/src/main/java/org/parabot/core/asm/wrappers/Callback.java
index 039b41c..5917f0f 100644
--- a/src/main/java/org/parabot/core/asm/wrappers/Callback.java
+++ b/src/main/java/org/parabot/core/asm/wrappers/Callback.java
@@ -26,14 +26,16 @@ public class Callback implements Injectable {
         this.invokeMethod = callbackMethod;
         this.desc = callbackDesc;
         this.conditional = conditional;
-        if (args.contains(",")) {
-            final String[] strArgs = args.split(",");
-            this.args = new int[strArgs.length];
-            for (int i = 0; i < this.args.length; i++) {
-                this.args[i] = Integer.parseInt(strArgs[i]);
+        if (args.length() > 0) {
+            if (args.contains(",")) {
+                final String[] strArgs = args.split(",");
+                this.args = new int[strArgs.length];
+                for (int i = 0; i < this.args.length; i++) {
+                    this.args[i] = Integer.parseInt(strArgs[i]);
+                }
+            } else {
+                this.args = new int[]{Integer.parseInt(args)};
             }
-        } else {
-            this.args = new int[]{ Integer.parseInt(args) };
         }
     }
 
diff --git a/src/main/java/org/parabot/core/parsers/hooks/XMLHookParser.java b/src/main/java/org/parabot/core/parsers/hooks/XMLHookParser.java
index af01411..acde8cf 100644
--- a/src/main/java/org/parabot/core/parsers/hooks/XMLHookParser.java
+++ b/src/main/java/org/parabot/core/parsers/hooks/XMLHookParser.java
@@ -67,6 +67,12 @@ public class XMLHookParser extends HookParser {
     private static final String getValue(String tag, Element element) {
         NodeList nodes = element.getElementsByTagName(tag).item(0)
                 .getChildNodes();
+        if (nodes.getLength() == 0 || nodes.item(0) == null) {
+            if (Core.inVerboseMode()) {
+                System.err.println("WARNING: Invalid Hook "+tag+" subnode. Tag is missing or empty?");
+            }
+            return "";
+        }
         Node node = (Node) nodes.item(0);
         return node.getNodeValue();
     }