--- Compress-LZF/LZF.xs	2001/09/27 19:51:26	1.3
+++ Compress-LZF/LZF.xs	2001/09/27 20:05:38	1.4
@@ -21,8 +21,9 @@
 #define MAGIC_LO	0
 #define MAGIC_U		0 /* uncompressed data follows */
 #define MAGIC_C		1 /* compressed data follows */
-#define MAGIC_R		4 /* storable (reference, freeze) */
+#define MAGIC_undef	2 /* the special value undef */
 #define MAGIC_CR	3 /* storable (reference, freeze), compressed */
+#define MAGIC_R		4 /* storable (reference, freeze) */
 #define MAGIC_HI	7 /* room for one higher storable major */
 
 #define IN_RANGE(v,l,h) ((unsigned int)((unsigned)(v) - (unsigned)(l)) <= (unsigned)(h) - (unsigned)(l))
@@ -225,7 +226,9 @@
         PROTOTYPE: $
         PPCODE:
 
-        if (SvTYPE(sv) != SVt_IV
+        if (!SvOK (sv))
+          XPUSHs (sv_2mortal (newSVpvn ("\02", 1))); /* 02 == MAGIC_undef */
+        else if (SvTYPE(sv) != SVt_IV
             && SvTYPE(sv) != SVt_NV
             && SvTYPE(sv) != SVt_PV) /* mstore */
           {
@@ -251,7 +254,7 @@
             else
               XPUSHs (sv);
           }
-        else if (IN_RANGE (SvPVX (sv)[0], MAGIC_LO, MAGIC_HI))
+        else if (sv && IN_RANGE (SvPVX (sv)[0], MAGIC_LO, MAGIC_HI))
           XPUSHs (sv_2mortal (compress_sv (sv, MAGIC_C, 1))); /* need to prefix only */
         else if (ix == 2) /* compress always */
           XPUSHs (sv_2mortal (compress_sv (sv, MAGIC_C, 0)));
@@ -263,12 +266,15 @@
 	SV *	sv
         PROTOTYPE: $
         PPCODE:
-        char hdr = SvPVX (sv)[0];
 
-        if (IN_RANGE (hdr, MAGIC_LO, MAGIC_HI))
+        if (IN_RANGE (SvPV_nolen (sv)[0], MAGIC_LO, MAGIC_HI))
           {
             switch (SvPVX (sv)[0])
               {
+                case MAGIC_undef:
+                  XPUSHs (sv_2mortal (NEWSV (0, 0)));
+                  break;
+
                 case MAGIC_U:
                   XPUSHs (sv_2mortal (decompress_sv (sv, 0)));
                   break;
@@ -292,7 +298,7 @@
 
                   SPAGAIN;
 
-                  /*XPUSHs (POPs);*/
+                  XPUSHs (POPs); /* this is a nop, hope the compiler also knows this */
 
                   break;