diff --git a/SearchStrategy.hs b/SearchStrategy.hs
index 5d85d2e..9944332 100644
--- a/SearchStrategy.hs
+++ b/SearchStrategy.hs
@@ -25,7 +25,7 @@ import Debug.Trace (trace)
 -- | @isTick N t k@ is a clock that ticks @t@ times as 
 -- @k@ ranges over the interval [1..N].  It's used for
 -- emitting diagnostic output at regular intervals of a search
-isTick denom numIntervals num =
+isTick denom numIntervals num = denom > 0 &&
   num * numIntervals `div` denom > (num - 1) * numIntervals `div` denom
 
 tickProp (Positive n') (Positive t) =
diff --git a/testing/sandwich.fasta b/testing/sandwich.fasta
new file mode 100644
index 0000000..a886e8b
--- /dev/null
+++ b/testing/sandwich.fasta
@@ -0,0 +1,5 @@
+> d2sbaa_ b.29.1.1 (A:) Legume lectin {Soybean (Glycine max) [TaxId: 3847]}
+AETVSFSWNKFVPKQPNMILQGDAIVTSSGKLQLNKVDENGTPKPSSLGRALYSTPIHIW
+DKETGSVASFAASFNFTFYAPDTKRLADGLAFFLAPIDTKPQTHAGYLGLFNENESGDQV
+VAVEFDTFRNSWDPPNPHIGINVNSIRSIKTTSWDLANNKVAKVLITYDASTSLLVASLV
+YPSQRTSNILSDVVDLKTSLPEWVRIGFSAATGLDIPGESHDVLSWSFASNLPHA
\ No newline at end of file