diff --git a/lib/importproject.h b/lib/importproject.h
index 7163a7642..1933c87f8 100644
--- a/lib/importproject.h
+++ b/lib/importproject.h
@@ -30,7 +30,6 @@
 #include <set>
 #include <string>
 #include <vector>
-#include <cctype>
 
 /// @addtogroup Core
 /// @{
diff --git a/lib/utils.h b/lib/utils.h
index bc3482339..d6bc1b26b 100644
--- a/lib/utils.h
+++ b/lib/utils.h
@@ -22,6 +22,7 @@
 //---------------------------------------------------------------------------
 
 #include <algorithm>
+#include <cctype>
 #include <cstddef>
 #include <string>