diff --git a/include/kpn/diagnostics.hpp b/include/kpn/diagnostics.hpp
index 884d668..f760c81 100644
--- a/include/kpn/diagnostics.hpp
+++ b/include/kpn/diagnostics.hpp
@@ -4,6 +4,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <string>
+#include <vector>
 #include <time.h>   // clock_gettime, CLOCK_THREAD_CPUTIME_ID
 
 namespace kpn {