diff --git a/src/mt_math.h b/src/mt_math.h
index 7e6c1ae..0820bd8 100644
--- a/src/mt_math.h
+++ b/src/mt_math.h
@@ -3,6 +3,6 @@
 
 #include <math.h>
 
-#define digits(num) (num == 0) ? 1 : (int) (floor(log10(fabs(num))) + 1)
+#define digits(num) (num == 0) ? 1 : (int) (floor(log10(abs(num))) + 1)
 
 #endif