diff --git a/java/src/org/broadinstitute/sting/commandline/ArgumentTypeDescriptor.java b/java/src/org/broadinstitute/sting/commandline/ArgumentTypeDescriptor.java
index 7847f4575..f17428570 100644
--- a/java/src/org/broadinstitute/sting/commandline/ArgumentTypeDescriptor.java
+++ b/java/src/org/broadinstitute/sting/commandline/ArgumentTypeDescriptor.java
@@ -299,6 +299,7 @@ class SimpleArgumentTypeDescriptor extends ArgumentTypeDescriptor {
     public Object parse(ParsingEngine parsingEngine, ArgumentSource source, Class type, ArgumentMatches matches) {
         if (source.isFlag())
             return true;
+
         ArgumentDefinition defaultDefinition = createDefaultArgumentDefinition(source);
         String value = getArgumentValue( defaultDefinition, matches );
         Object result;
@@ -308,6 +309,8 @@ class SimpleArgumentTypeDescriptor extends ArgumentTypeDescriptor {
         try {
             if (type.isPrimitive()) {
                 Method valueOf = primitiveToWrapperMap.get(type).getMethod("valueOf",String.class);
+                if(value == null)
+                    throw new MissingArgumentValueException(createDefaultArgumentDefinition(source));
                 result = valueOf.invoke(null,value.trim());
             } else if (type.isEnum()) {
                 Object[] vals = type.getEnumConstants();
diff --git a/java/test/org/broadinstitute/sting/commandline/ParsingEngineUnitTest.java b/java/test/org/broadinstitute/sting/commandline/ParsingEngineUnitTest.java
index 74d881fe9..54e3b35bc 100755
--- a/java/test/org/broadinstitute/sting/commandline/ParsingEngineUnitTest.java
+++ b/java/test/org/broadinstitute/sting/commandline/ParsingEngineUnitTest.java
@@ -125,6 +125,20 @@ public class ParsingEngineUnitTest extends BaseTest {
         Assert.assertEquals(argProvider.foo, 5, "Argument is not correctly initialized");
     }
 
+    @Test(expectedExceptions=MissingArgumentValueException.class)
+    public void primitiveArgumentNoValueTest() {
+        final String[] commandLine = new String[] {"--foo"};
+
+        parsingEngine.addArgumentSource( PrimitiveArgProvider.class );
+        parsingEngine.parse( commandLine );
+        parsingEngine.validate();
+
+        PrimitiveArgProvider argProvider = new PrimitiveArgProvider();
+        parsingEngine.loadArgumentsIntoObject( argProvider );
+
+        Assert.assertEquals(argProvider.foo, 5, "Argument is not correctly initialized");
+    }
+
     private class PrimitiveArgProvider {
         @Argument(doc="simple integer")
         int foo;