diff --git a/core/build.xml b/core/build.xml
index 7fe5fe803..c76c70993 100644
--- a/core/build.xml
+++ b/core/build.xml
@@ -23,7 +23,6 @@
   <path id="javame-compile-bootclasspath">
     <fileset dir="${WTK-home}/lib">
       <include name="cldcapi11.jar"/>
-      <include name="midpapi20.jar"/>
     </fileset>
   </path>
   <property name="javame-compile-bootclasspath-path" refid="javame-compile-bootclasspath"/>
@@ -46,7 +45,25 @@
     <jar jarfile="core.jar" basedir="build" level="9"/>
   </target>
 
-  <target name="build-test" depends="init,build">
+  <target name="build-optimized" depends="build">
+    <move file="core.jar" tofile="temp.jar"/>
+    <java jar="${WTK-home}/bin/proguard.jar" fork="true" failonerror="true">
+      <jvmarg value="-Dmaximum.inlined.code.length=32"/>
+      <arg value="-injars temp.jar"/>
+      <arg value="-outjars core.jar"/>
+      <arg value="-libraryjars ${WTK-home}/lib/cldcapi11.jar"/>
+      <arg value="-renamesourcefileattribute SourceFile"/>
+      <arg value="-keepattributes Exceptions,InnerClasses,Signature,Deprecated,SourceFile,LineNumberTable,*Annotation*,EnclosingMethod"/>
+      <arg value="-keep class * { !private *; }"/>
+      <arg value="-optimizationpasses 7"/>
+      <arg value="-overloadaggressively"/>
+      <arg value="-allowaccessmodification"/>
+      <arg value="-verbose"/>
+    </java>
+    <delete file="temp.jar"/>
+  </target>
+
+  <target name="build-test" depends="init,build-optimized">
     <fail message="Please build 'javase' first">
       <condition>
         <not>
@@ -60,7 +77,7 @@
            debug="true"
            deprecation="true">
       <classpath>
-        <pathelement location="build"/>
+        <pathelement location="core.jar"/>
         <pathelement location="../javase/javase.jar"/>
         <pathelement location="lib/junit.jar"/>
       </classpath>
@@ -71,7 +88,7 @@
     <junit printsummary="on" haltonfailure="on" haltonerror="on" fork="true" dir=".">
       <formatter type="plain" usefile="false"/>
       <classpath>
-        <pathelement location="build"/>
+        <pathelement location="core.jar"/>
         <pathelement location="build-test"/>
         <pathelement location="../javase/javase.jar"/>
         <pathelement location="lib/junit.jar"/>
@@ -92,7 +109,7 @@
     <junit printsummary="on" haltonfailure="on" haltonerror="on" fork="true" dir=".">
       <formatter type="plain" usefile="false"/>
       <classpath>
-        <pathelement location="build"/>
+        <pathelement location="core.jar"/>
         <pathelement location="build-test"/>
         <pathelement location="../javase/javase.jar"/>
         <pathelement location="lib/junit.jar"/>
diff --git a/core/src/com/google/zxing/MonochromeBitmapSource.java b/core/src/com/google/zxing/MonochromeBitmapSource.java
index ccecbd373..b828b94bc 100644
--- a/core/src/com/google/zxing/MonochromeBitmapSource.java
+++ b/core/src/com/google/zxing/MonochromeBitmapSource.java
@@ -103,7 +103,7 @@ public interface MonochromeBitmapSource {
    * of this class which are only used in resource-constrained mobile environments
    * don't have a need to implement this.</p>
    *
-   * @throws IllegalStateException if not supported
+   * @throws IllegalArgumentException if not supported
    */
   MonochromeBitmapSource rotateCounterClockwise();
 
diff --git a/core/src/com/google/zxing/common/BaseMonochromeBitmapSource.java b/core/src/com/google/zxing/common/BaseMonochromeBitmapSource.java
index e6906b408..559dbefe6 100644
--- a/core/src/com/google/zxing/common/BaseMonochromeBitmapSource.java
+++ b/core/src/com/google/zxing/common/BaseMonochromeBitmapSource.java
@@ -112,7 +112,7 @@ public abstract class BaseMonochromeBitmapSource implements MonochromeBitmapSour
   }
 
   public MonochromeBitmapSource rotateCounterClockwise() {
-    throw new IllegalStateException("Rotate not supported");
+    throw new IllegalArgumentException("Rotate not supported");
   }
 
   public boolean isRotateSupported() {
diff --git a/core/src/com/google/zxing/datamatrix/decoder/DataBlock.java b/core/src/com/google/zxing/datamatrix/decoder/DataBlock.java
index 4bcbb3a7a..009fb00d7 100644
--- a/core/src/com/google/zxing/datamatrix/decoder/DataBlock.java
+++ b/core/src/com/google/zxing/datamatrix/decoder/DataBlock.java
@@ -101,7 +101,7 @@ final class DataBlock {
     }
 
     if (rawCodewordsOffset != rawCodewords.length) {
-      throw new IllegalStateException();
+      throw new IllegalArgumentException();
     }
 
     return result;
diff --git a/core/src/com/google/zxing/qrcode/decoder/DataBlock.java b/core/src/com/google/zxing/qrcode/decoder/DataBlock.java
index 995a0d60b..50fadd13e 100755
--- a/core/src/com/google/zxing/qrcode/decoder/DataBlock.java
+++ b/core/src/com/google/zxing/qrcode/decoder/DataBlock.java
@@ -80,7 +80,7 @@ final class DataBlock {
         break;
       }
       if (numCodewords != shorterBlocksTotalCodewords + 1) {
-        throw new IllegalStateException("Data block sizes differ by more than 1");
+        throw new IllegalArgumentException("Data block sizes differ by more than 1");
       }
       longerBlocksStartAt--;
     }
@@ -109,7 +109,7 @@ final class DataBlock {
     }
 
     if (rawCodewordsOffset != rawCodewords.length) {
-      throw new IllegalStateException();
+      throw new IllegalArgumentException();
     }
 
     return result;