diff --git a/devito/ir/iet/algorithms.py b/devito/ir/iet/algorithms.py
index 0060c544f8..9d2db185db 100644
--- a/devito/ir/iet/algorithms.py
+++ b/devito/ir/iet/algorithms.py
@@ -6,7 +6,6 @@
 from devito.petsc.types import LinearSolveExpr
 from devito.petsc.iet.utils import petsc_iet_mapper
 
-
 __all__ = ['iet_build']
 
 
diff --git a/devito/passes/iet/mpi.py b/devito/passes/iet/mpi.py
index a1fa772a7b..b7f6572a26 100644
--- a/devito/passes/iet/mpi.py
+++ b/devito/passes/iet/mpi.py
@@ -79,7 +79,6 @@ def rule1(dep, candidates, loc_dims):
     rules = [rule0, rule1]
 
     # Precompute scopes to save time
-    # TODO: Investigate
     scopes = {i: Scope([e.expr for e in v if not isinstance(e, Call)])
               for i, v in MapNodes().visit(iet).items()}
 
diff --git a/devito/petsc/clusters.py b/devito/petsc/clusters.py
index 8ffe6a7eed..7208193dc2 100644
--- a/devito/petsc/clusters.py
+++ b/devito/petsc/clusters.py
@@ -26,7 +26,6 @@ def petsc_project(clusters):
     """
     processed = []
     for c in clusters:
-        # Drop time-loop for expressions that appear in PETSc callback functions
         if isinstance(c.exprs[0].rhs, CallbackExpr):
             time_dims = [d for d in c.ispace.intervals.dimensions if d.is_Time]
             ispace = c.ispace.project(lambda d: d not in time_dims)