diff --git a/src/machine.cpp b/src/machine.cpp
index 33d1599f20..f05ba92d39 100644
--- a/src/machine.cpp
+++ b/src/machine.cpp
@@ -869,9 +869,10 @@ parsePoolEntry(Thread* t, Stream& s, uint32_t* index, object pool, unsigned i)
 
       parsePoolEntry(t, s, index, pool, ci);
       parsePoolEntry(t, s, index, pool, nti);
-        
+
       object class_ = referenceName(t, singletonObject(t, pool, ci));
       object nameAndType = singletonObject(t, pool, nti);
+
       object value = makeReference
           (t, class_, pairFirst(t, nameAndType), pairSecond(t, nameAndType));
       set(t, pool, SingletonBody + (i * BytesPerWord), value);
@@ -3228,7 +3229,9 @@ isAssignableFrom(Thread* t, object a, object b)
       return isAssignableFrom
         (t, classStaticTable(t, a), classStaticTable(t, b));
     }
-  } else {
+  } else if ((classVmFlags(t, a) & PrimitiveFlag)
+             == (classVmFlags(t, b) & PrimitiveFlag))
+  {
     for (; b; b = classSuper(t, b)) {
       if (b == a) {
         return true;
diff --git a/src/machine.h b/src/machine.h
index 96c853624f..83ea2577a4 100644
--- a/src/machine.h
+++ b/src/machine.h
@@ -2164,6 +2164,8 @@ hashTaken(Thread*, object o)
 inline unsigned
 baseSize(Thread* t, object o, object class_)
 {
+  assert(t, classFixedSize(t, class_) >= BytesPerWord);
+
   return ceiling(classFixedSize(t, class_), BytesPerWord)
     + ceiling(classArrayElementSize(t, class_)
               * cast<uintptr_t>(o, classFixedSize(t, class_) - BytesPerWord),
diff --git a/test/Misc.java b/test/Misc.java
index 7ff2f25378..450f23d2b0 100644
--- a/test/Misc.java
+++ b/test/Misc.java
@@ -235,5 +235,7 @@ public class Misc {
     System.out.println(75.62);
     System.out.println(75.62d);
     System.out.println(new char[] { 'h', 'i' });
+
+    expect(! (((Object) new int[0]) instanceof Object[]));
   }
 }