diff --git a/filters_preprint.yaml b/filters_preprint.yaml
index 743abdc..2b938a5 100644
--- a/filters_preprint.yaml
+++ b/filters_preprint.yaml
@@ -1,4 +1,7 @@
-bad_mutations: 
+controls:
+  - sample ~ /^control/
+
+bad_mutations:
   - proto v3
   - mutations in [ 28461G, 11201G, 26801C, -28461G, -11201G, -26801C ]
 
diff --git a/lollipop/preprocessors.py b/lollipop/preprocessors.py
index 62af257..4a3de7d 100644
--- a/lollipop/preprocessors.py
+++ b/lollipop/preprocessors.py
@@ -186,12 +186,14 @@ def apply_filter_statement(name, fs):
                     )
                 case "~" | "=~" | "~=":
                     return col.str.contains(
-                        val[1, -2] if val[0] == val[-1] in "/@" else val
+                        val[1:-1] if not m["qv"] and val[0] == val[-1] in "/@" else val
                     )
                 case "!~" | "~!":
                     return ~(
                         col.str.contains(
-                            val[1, -2] if val[0] == val[-1] in "/@" else val
+                            val[1:-1]
+                            if not m["qv"] and val[0] == val[-1] in "/@"
+                            else val
                         )
                     )
                 case _ as o: