--- a/js/ctypes/Function.cpp
+++ b/js/ctypes/Function.cpp
@@ -243,16 +243,17 @@ PrepareValue(JSContext* aContext, const 
     aResult.mData = &aResult.mValue.mInt16;
     break;
   case nsIForeignLibrary::INT32:
     // Do not implicitly lose bits.
     if (!jsvalToIntStrict(aValue, &aResult.mValue.mInt32))
       return TypeError(aContext, "int32", aValue);
 
     aResult.mData = &aResult.mValue.mInt32;
+    break;
   case nsIForeignLibrary::INT64:
     // Do not implicitly lose bits.
     if (!jsvalToIntStrict(aValue, &aResult.mValue.mInt64))
       return TypeError(aContext, "int64", aValue);
 
     aResult.mData = &aResult.mValue.mInt64;
     break;
   case nsIForeignLibrary::UINT8:
@@ -270,16 +271,17 @@ PrepareValue(JSContext* aContext, const 
     aResult.mData = &aResult.mValue.mUint16;
     break;
   case nsIForeignLibrary::UINT32:
     // Do not implicitly lose bits.
     if (!jsvalToIntStrict(aValue, &aResult.mValue.mUint32))
       return TypeError(aContext, "uint32", aValue);
 
     aResult.mData = &aResult.mValue.mUint32;
+    break;
   case nsIForeignLibrary::UINT64:
     // Do not implicitly lose bits.
     if (!jsvalToIntStrict(aValue, &aResult.mValue.mUint64))
       return TypeError(aContext, "uint64", aValue);
 
     aResult.mData = &aResult.mValue.mUint64;
     break;
   case nsIForeignLibrary::FLOAT: