diff --git a/util/cmake/pro2cmake.py b/util/cmake/pro2cmake.py
index 51cce8027c0..df81974ef1e 100755
--- a/util/cmake/pro2cmake.py
+++ b/util/cmake/pro2cmake.py
@@ -1598,6 +1598,8 @@ def handle_subdir(
                 if condition_str and subtraction_str:
                     condition_str += " AND "
                 condition_str += subtraction_str
+                if not condition_str.rstrip("()").strip():
+                    continue
                 condition_simplified = simplify_condition(condition_str)
                 condition_key = condition_simplified