diff --git a/src/flog.h b/src/flog.h
index f726284c6..f85f1b647 100644
--- a/src/flog.h
+++ b/src/flog.h
@@ -61,6 +61,7 @@ class category_list_t {
 
     category_t exec_fork{L"exec-fork", L"Calls to fork()"};
 
+    category_t output_invalid{L"output-invalid", L"Trying to print invalid output"};
     category_t parse_productions{L"parse-productions", L"Resolving tokens"};
     category_t parse_productions_chatty{L"parse-productions-chatty",
                                         L"Resolving tokens (chatty messages)"};
diff --git a/src/output.cpp b/src/output.cpp
index b646b3076..f641bcb12 100644
--- a/src/output.cpp
+++ b/src/output.cpp
@@ -404,7 +404,7 @@ void outputter_t::writestr(const wchar_t *str) {
 
     size_t len = wcstombs(nullptr, str, 0);  // figure amount of space needed
     if (len == static_cast<size_t>(-1)) {
-        FLOGF(warning, L"Tried to print invalid wide character string");
+        FLOGF(output_invalid, L"Tried to print invalid wide character string");
         return;
     }