1 files changed, 1 insertions, 1 deletions
diff --git a/signpost.c b/signpost.c
index 70b444a..aeb32ea 100644
--- a/signpost.c
+++ b/signpost.c
@@ -8,7 +8,7 @@
 #include <assert.h>
 #include <ctype.h>
 #include <limits.h>
-#include <math.h>
+#include <tgmath.h>
 
 #include "puzzles.h"