diff --git a/backend/app/plan/validation/courses/simplify.py b/backend/app/plan/validation/courses/simplify.py
index 20dceefd..af792d0f 100644
--- a/backend/app/plan/validation/courses/simplify.py
+++ b/backend/app/plan/validation/courses/simplify.py
@@ -242,9 +242,7 @@ def _anihil_rule(
         new.clear()
         new.append(Const(value=not op.neutral))
         anihilate[0] = True
-    if anihilate[0]:
-        return True
-    return False
+    return bool(anihilate[0])
 
 
 def anihil(expr: Operator) -> Expr:
@@ -255,10 +253,8 @@ def anihil(expr: Operator) -> Expr:
 
 
 def _ident_rule(ctx: None, op: Operator, new: list[Expr], child: Expr) -> bool:
-    if isinstance(child, Const) and child.value == op.neutral:
-        # Skip this child, since it adds nothing to the expression
-        return True
-    return False
+    # Skip this child, since it adds nothing to the expression
+    return isinstance(child, Const) and child.value == op.neutral
 
 
 def ident(expr: Operator) -> Expr:
diff --git a/backend/app/plan/validation/courses/validate.py b/backend/app/plan/validation/courses/validate.py
index 4b44510b..550b2f34 100644
--- a/backend/app/plan/validation/courses/validate.py
+++ b/backend/app/plan/validation/courses/validate.py
@@ -553,6 +553,4 @@ def is_course_indirectly_available(courseinfo: CourseInfo, code: str):
     info = courseinfo.try_course(code)
     if info is None:
         return False
-    if courseinfo.is_available(info.canonical_equiv):
-        return True
-    return False
+    return courseinfo.is_available(info.canonical_equiv)
diff --git a/backend/app/sync/curriculums/scrape/translate.py b/backend/app/sync/curriculums/scrape/translate.py
index 615c0477..5290b87b 100644
--- a/backend/app/sync/curriculums/scrape/translate.py
+++ b/backend/app/sync/curriculums/scrape/translate.py
@@ -66,7 +66,7 @@ def __init__(
             if bloque.CodSigla is not None:
                 equivalents: list[str] = [bloque.CodSigla]
                 if bloque.Equivalencias is not None:
-                    for equivalent in bloque.Equivalencias.Cursos:
+                    for equivalent in bloque.Equivalencias.Cursos or []:
                         if equivalent.Sigla is not None:
                             equivalents.append(equivalent.Sigla)
                 if len(equivalents) > 1:
diff --git a/backend/app/sync/curriculums/siding.py b/backend/app/sync/curriculums/siding.py
index df1ef005..55a7c205 100644
--- a/backend/app/sync/curriculums/siding.py
+++ b/backend/app/sync/curriculums/siding.py
@@ -151,7 +151,7 @@ def _filter_relevant_cyears(cyears: StringArray | None) -> bool:
     if cyears is None:
         return False
     cyears.strings.string = [
-        cyear for cyear in cyears.strings.string if cyear >= IGNORE_CYEARS_BEFORE
+        cyear for cyear in cyears.strings.string or [] if cyear >= IGNORE_CYEARS_BEFORE
     ]
     return len(cyears.strings.string) > 0
 
@@ -161,7 +161,7 @@ async def _fetch_siding_plans(siding: SidingInfo):
     for major in siding.majors:
         if major.Curriculum is None:
             continue
-        for cyear_str in major.Curriculum.strings.string:
+        for cyear_str in major.Curriculum.strings.string or []:
             cyear = cyear_from_str(cyear_str)
             if cyear is None:
                 log.error(
@@ -184,7 +184,7 @@ async def _fetch_siding_plans(siding: SidingInfo):
     for minor in siding.minors:
         if minor.Curriculum is None:
             continue
-        for cyear_str in minor.Curriculum.strings.string:
+        for cyear_str in minor.Curriculum.strings.string or []:
             cyear = cyear_from_str(cyear_str)
             if cyear is None:
                 log.error(
@@ -207,7 +207,7 @@ async def _fetch_siding_plans(siding: SidingInfo):
     for title in siding.titles:
         if title.Curriculum is None:
             continue
-        for cyear_str in title.Curriculum.strings.string:
+        for cyear_str in title.Curriculum.strings.string or []:
             cyear = cyear_from_str(cyear_str)
             if cyear is None:
                 log.error(
@@ -278,7 +278,7 @@ def translate_siding(
             codes = [main_code]
             if raw_block.Equivalencias is not None:
                 # Add equivalences to the list
-                for curso in raw_block.Equivalencias.Cursos:
+                for curso in raw_block.Equivalencias.Cursos or []:
                     if curso.Sigla is not None and curso.Sigla != main_code:
                         codes.append(curso.Sigla)
             list_code = (
@@ -385,7 +385,7 @@ def _fill_in_c2022_titles(courses: dict[str, CourseDetails], siding: SidingInfo)
         if title.Curriculum is None:
             continue
         cyears = title.Curriculum.strings.string
-        if "C2020" in cyears and "C2022" not in cyears:
+        if cyears and "C2020" in cyears and "C2022" not in cyears:
             cyears.append("C2022")
             siding.plans["C2022"].plans[title.CodTitulo] = siding.plans["C2020"].plans[
                 title.CodTitulo
diff --git a/backend/app/sync/siding/translate.py b/backend/app/sync/siding/translate.py
index 5a838dfd..6d2e55d3 100644
--- a/backend/app/sync/siding/translate.py
+++ b/backend/app/sync/siding/translate.py
@@ -51,7 +51,7 @@ def _decode_curriculum_versions(input: StringArray | None) -> list[str]:
         # too unreliable
         logging.warning("null curriculum version list")
         return []
-    return input.strings.string
+    return input.strings.string or []
 
 
 def _decode_period(period: str) -> tuple[int, int]: