diff --git a/VERSIONLOG.md b/VERSIONLOG.md
index 3f82273..d026c4b 100644
--- a/VERSIONLOG.md
+++ b/VERSIONLOG.md
@@ -1,5 +1,8 @@
 # Flowcell Parser Version Log
 
+## 20260918.1
+Update Illumina runfolder regex
+
 ## 20251104.1
 Remove unused db module 
 
diff --git a/flowcell_parser/classes.py b/flowcell_parser/classes.py
index 90ae2e6..683249c 100755
--- a/flowcell_parser/classes.py
+++ b/flowcell_parser/classes.py
@@ -32,7 +32,7 @@ def __init__(self, path):
 
     def parse(self, demultiplexing_dir='Demultiplexing'):
         """Tries to parse as many files as possible from a run folder"""
-        pattern = r'(\d{6,8})_([ST-]*\w+\d+)_\d+_([AB]?)([A-Z0-9\-]+)'
+        pattern = r"^(\d{6,8})_([a-zA-Z\d\-]+)_\d+_([AB]?)([A-Z\d\-]+)$"
         m = re.match(pattern, os.path.basename(os.path.abspath(self.path)))
         instrument = m.group(2)
         # NextSeq2000 has a different FC ID pattern that ID contains the first position letter