diff --git a/crisprbact/predict.py b/crisprbact/predict.py
index 1b3821eff32bfe45584ed96e29b116f4dfc3ac72..f0e09b8c99b57f5c2b31407070dbff2d46b8a1d3 100644
--- a/crisprbact/predict.py
+++ b/crisprbact/predict.py
@@ -35,13 +35,13 @@ def find_targets(seq):
     for target in matching_targets:
         matching_target = target.group(1)
         start, end = target.span(1)
-        start_min = 13
+        start_min = 14
         if start >= start_min:
             guide_start = start - start_min
-            guide_end = start + 7
+            guide_end = end - 16 - 3
             guide = seq_revcomp[guide_start:guide_end]
             assert len(guide) == 20
-            pos_seq_start = L - guide_start - 20
+            pos_seq_start = L - guide_end
             pos_seq_stop = L - guide_start
             pos_seq_pam = pos_seq_start - 3
             yield dict(