diff --git a/check_source/check_spelling_c_config.py b/check_source/check_spelling_c_config.py
index d68123392eebb617214bf571e9de46a28c24ef53..f0dea40e833dd6d3b723026fcf150f398d62b4ff 100644
--- a/check_source/check_spelling_c_config.py
+++ b/check_source/check_spelling_c_config.py
@@ -130,6 +130,7 @@ dict_custom = {
     "homogenous",
     "ideographic",
     "illuminant",
+    "impactful",
     "incrementation",
     "initializer",
     "initializers",