diff --git a/src/dxtbx/model/scan_helpers.py b/src/dxtbx/model/scan_helpers.py
index a08bafcc5..c1b2a3302 100644
--- a/src/dxtbx/model/scan_helpers.py
+++ b/src/dxtbx/model/scan_helpers.py
@@ -14,10 +14,11 @@
     r"([0-9]{2,12})\.(.*)",
     r"(.*)\.([0-9]{2,12})_(.*)",
     r"(.*)\.([0-9]{2,12})(.*)",
-    r"(.*)\.([0-9]{1,12})(.*)",
+    r"(.*)\.([0-9]{1,12})_(.*)",
+    r"(.*)\.([0-9]{1})(.*)",
 ]
 
-joiners = [".", "_", "", ""]
+joiners = [".", "_", "", "_", ""]
 
 compiled_patterns = [re.compile(pattern) for pattern in patterns]