=== autobox.pm
==================================================================
--- autobox.pm	(revision 451)
+++ autobox.pm	(local)
@@ -23,7 +23,10 @@
 # defaults and/or allow a wider or narrower range of types to be autoboxed.
 
 my $TYPEMAP = {
-    SCALAR	=> 'SCALAR',
+    SCALAR      => 'SCALAR',
+    INTEGER     => 'INTEGER',
+    STRING      => 'STRING',
+    FLOAT       => 'FLOAT',
     ARRAY	=> 'ARRAY',
     HASH	=> 'HASH',
     CODE	=> 'CODE',
@@ -76,7 +79,7 @@
 		$args{$key} = $typemap->{$key};
 	    } # else: already defined
 	} else {
-	    if ((defined $default) && ($default eq '')) {
+	    if ((defined $default) && ($default eq '') || ($key =~ /(?:INTEGER|STRING|FLOAT)/)) {
 		$args{$key} = $typemap->{$key};
 	    } else {
 		$args{$key} = $default; # namespace expansion is handled below
=== autobox.xs
==================================================================
--- autobox.xs	(revision 451)
+++ autobox.xs	(local)
@@ -98,9 +98,45 @@
 	    SV **svp; /* pointer to autobox_handlers value */
 
 	    /* determine the package from the receiver's reftype() - or "UNDEF" if it's not a ref */
-	    reftype = SvOK(sv) ? sv_reftype((SvROK(sv) ? SvRV(sv) : sv), 0) : "UNDEF";
+            if (SvOK(sv)) {
+                if (SvROK(sv)) {
+                    reftype = sv_reftype(SvRV(sv), 0);
+                } else {
+                    switch (SvTYPE(sv)) {
+                        case SVt_IV:
+                            reftype = "INTEGER";
+                            break;
+                        case SVt_NV:
+                            reftype = "FLOAT";
+                            break;
+                        case SVt_PV:
+                            reftype = "STRING";
+                            break;
+                        default:
+                            // TODO: throw fatal error
+                            reftype = "SCALAR";
+                            break;
+                    }
+                }
+            } else {
+                reftype = "UNDEF";
+            }
 	    svp = hv_fetch(autobox_handlers, reftype, strlen(reftype), 0);
 
+	    if (svp && SvOK(*svp) && SvOK(sv) && !SvROK(sv)) {
+		/* check undefined class for SCALAR types */
+
+		packsv = *svp;
+		packname = SvPVX(packsv); /* fake the package name */
+		packlen = strlen(packname);
+		stash = gv_stashpvn(packname, packlen, FALSE);
+
+		if ((long)HvTOTALKEYS(stash) < 3) {;
+		    /* undefined class */
+		    svp = hv_fetch(autobox_handlers, "SCALAR", 6, 0);
+		}
+	    }
+
 	    if (svp && SvOK(*svp)) {
 		packsv = *svp;
 		packname = SvPVX(packsv); /* fake the package name */