diff --git a/perllib/phash.ph b/perllib/phash.ph
index 936978a5..8142c4ef 100644
--- a/perllib/phash.ph
+++ b/perllib/phash.ph
@@ -146,7 +146,7 @@ sub gen_perfect_hash($) {
     # Minimal power of 2 value for N with enough wiggle room.
     # The scaling constant must be larger than 0.5 in order for the
     # algorithm to ever terminate.
-    my $room = scalar(@keys)*0.8;
+    my $room = int(scalar(@keys)*0.8);
     $n = 1;
     while ($n < $room) {
 	$n <<= 1;