diff --git a/src/brut/androlib/err/UndefinedResourceSpec.java b/src/brut/androlib/err/UndefinedResourceSpec.java
new file mode 100644
index 00000000..7d68e963
--- /dev/null
+++ b/src/brut/androlib/err/UndefinedResourceSpec.java
@@ -0,0 +1,40 @@
+/*
+ *  Copyright 2010 Ryszard Wiśniewski <brut.alll@gmail.com>.
+ * 
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ * 
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *  under the License.
+ */
+
+package brut.androlib.err;
+
+import brut.androlib.AndrolibException;
+
+/**
+ * @author Ryszard Wiśniewski <brut.alll@gmail.com>
+ */
+public class UndefinedResourceSpec extends AndrolibException {
+    public UndefinedResourceSpec(Throwable cause) {
+        super(cause);
+    }
+
+    public UndefinedResourceSpec(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public UndefinedResourceSpec(String message) {
+        super(message);
+    }
+
+    public UndefinedResourceSpec() {
+    }
+}
diff --git a/src/brut/androlib/res/data/ResPackage.java b/src/brut/androlib/res/data/ResPackage.java
index a555c97a..84e31298 100644
--- a/src/brut/androlib/res/data/ResPackage.java
+++ b/src/brut/androlib/res/data/ResPackage.java
@@ -17,6 +17,7 @@
 
 package brut.androlib.res.data;
 
+import brut.androlib.err.UndefinedResourceSpec;
 import brut.androlib.AndrolibException;
 import brut.androlib.res.data.value.ResFileValue;
 import brut.androlib.res.data.value.ResValue;
@@ -58,10 +59,10 @@ public class ResPackage {
         return mResSpecs.containsKey(resID);
     }
 
-    public ResResSpec getResSpec(ResID resID) throws AndrolibException {
+    public ResResSpec getResSpec(ResID resID) throws UndefinedResourceSpec {
         ResResSpec spec = mResSpecs.get(resID);
         if (spec == null) {
-            throw new AndrolibException("Undefined resource spec: " + resID);
+            throw new UndefinedResourceSpec(resID.toString());
         }
         return spec;
     }