1 files changed, 1 insertions, 1 deletions
diff --git a/untangle.c b/untangle.c
index cd1762f..558cce7 100644
--- a/untangle.c
+++ b/untangle.c
@@ -32,7 +32,7 @@
 #include <assert.h>
 #include <ctype.h>
 #include <limits.h>
-#include <math.h>
+#include <tgmath.h>
 
 #include "puzzles.h"
 #include "tree234.h"