diff --git a/cppcheck_suppressions.conf b/cppcheck_suppressions.conf
index e0e750bfa..9a2160890 100644
--- a/cppcheck_suppressions.conf
+++ b/cppcheck_suppressions.conf
@@ -17,3 +17,6 @@ unusedPrivateFunction:src/blackmisc/tuple_private.h
 // cppcheck shouldn’t assume operator* is commutative
 duplicateExpression:tests/blackmisc/testvectormatrix.cpp
 duplicateExpression:tests/blackmisc/testphysicalquantities.cpp
+
+// Ignore any preprocessor directives.
+preprocessorErrorDirective