diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index 33c3a7f6c080b97067ff5360f974b9048013dd49..b5e9369593fbb29011016e8eafc9e3ec7b45c3fc 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -1528,6 +1528,7 @@ fixCppIncludeInsertions(StringRef Code, const tooling::Replacements &Replaces,
     bool Matched = IncludeRegex.match(IncludeDirective, &Matches);
     assert(Matched && "Header insertion replacement must have replacement text "
                       "'#include ...'");
+    (void)Matched;
     auto IncludeName = Matches[2];
     int Category =
         Categories.getIncludePriority(IncludeName, /*CheckMainHeader=*/true);