diff --git a/src/ISO8601.cpp b/src/ISO8601.cpp
index 6b4b16559..fe885ed1c 100644
--- a/src/ISO8601.cpp
+++ b/src/ISO8601.cpp
@@ -28,6 +28,7 @@
 #include <sstream>
 #include <stdlib.h>
 #include <Lexer.h>
+#include <util.h>
 #include <ISO8601.h>
 #include <Date.h>
 
diff --git a/src/Nibbler.cpp b/src/Nibbler.cpp
index b2d020f28..88d7b9f32 100644
--- a/src/Nibbler.cpp
+++ b/src/Nibbler.cpp
@@ -31,6 +31,7 @@
 #include <inttypes.h>
 #include <Lexer.h>
 #include <Nibbler.h>
+#include <util.h>
 #ifdef NIBBLER_FEATURE_DATE
 #include <Date.h>
 #endif