diff --git a/pyproject.toml b/pyproject.toml
index d08c406..bac2d7f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,7 @@
 # https://beta.ruff.rs/docs/configuration/#using-pyprojecttoml
 [tool.ruff]
-select = ["E", "F", "W"]
-ignore = ["W292", "E741"]
+select = ["E", "F", "W", "PIE", "C4", "ISC", "RUF100", "A"]
+ignore = ["W292", "E741", "E402", "C408", "ISC003"]
 line-length = 160
-target-version="py311"
\ No newline at end of file
+target-version="py311"
+flake8-implicit-str-concat.allow-multiline=false
diff --git a/rednose/helpers/ekf_sym.py b/rednose/helpers/ekf_sym.py
index b60c202..de68991 100644
--- a/rednose/helpers/ekf_sym.py
+++ b/rednose/helpers/ekf_sym.py
@@ -192,7 +192,7 @@ def gen_code(folder, name, f_sym, dt_sym, x_sym, obs_eqs, dim_x, dim_err, eskf_p
   for group, kinds in func_lists.items():
     post_code += f"  .{group}s = {{\n"
     for kind in kinds:
-      str_kind = f"\"{kind}\"" if type(kind) == str else kind
+      str_kind = f"\"{kind}\"" if isinstance(kind, str) else kind
       post_code += f"    {{ {str_kind}, {name}_{group}_{kind} }},\n"
     post_code += "  },\n"
   post_code += "  .extra_routines = {\n"
diff --git a/rednose/helpers/kalmanfilter.py b/rednose/helpers/kalmanfilter.py
index 0c30e49..d541faa 100644
--- a/rednose/helpers/kalmanfilter.py
+++ b/rednose/helpers/kalmanfilter.py
@@ -10,7 +10,8 @@ class KalmanFilter:
   Q = np.zeros((0, 0))
   obs_noise: Dict[int, Any] = {}
 
-  filter = None  # Should be initialized when initializating a KalmanFilter implementation
+  # Should be initialized when initializating a KalmanFilter implementation
+  filter = None # noqa: A003
 
   @property
   def x(self):