diff --git a/tools/mfkey/crapto1.c b/tools/mfkey/crapto1.c
index b6e0e87d5..ea7f60bba 100755
--- a/tools/mfkey/crapto1.c
+++ b/tools/mfkey/crapto1.c
@@ -551,7 +551,7 @@ struct Crypto1State* lfsr_common_prefix(uint32_t pfx, uint32_t rr, uint8_t ks[8]
 	odd = lfsr_prefix_ks(ks, 1);
 	even = lfsr_prefix_ks(ks, 0);
 
-	s = statelist = malloc((sizeof *statelist) << 20);
+	s = statelist = malloc((sizeof *statelist) << 24);
 	if(!s || !odd || !even) {
 		free(statelist);
 		statelist = 0;