diff --git a/focus_seq_FLI.py b/focus_seq_FLI.py
index 81b89ab..c00d86b 100755
--- a/focus_seq_FLI.py
+++ b/focus_seq_FLI.py
@@ -37,9 +37,9 @@ def init_seq(seq_kwds):
     if N > 0:
         max = 0
         for fname in foc_files:
-           inum = int(fname.stem.split('_')[1])
-           if inum > max:
-              max = inum
+            inum = int(fname.stem.split("_")[1])
+            if inum > max:
+                max = inum
 
         seq_kwds["start_idx"] = max + 1
 
diff --git a/focus_seq_Z1000_IXon.py b/focus_seq_Z1000_IXon.py
index 5ef0e62..0479d40 100755
--- a/focus_seq_Z1000_IXon.py
+++ b/focus_seq_Z1000_IXon.py
@@ -30,7 +30,13 @@ def init_seq(seq_kwds):
     seq_kwds["start_idx"] = 1
     N = len(foc_files)
     if N > 0:
-        seq_kwds["start_idx"] = N
+        max = 0
+        for fname in foc_files:
+            inum = int(fname.stem.split("_")[1])
+            if inum > max:
+                max = inum
+
+        seq_kwds["start_idx"] = max + 1
 
     return 0