diff --git a/src/string.c b/src/string.c
index f9d0791bd..c243e224f 100644
--- a/src/string.c
+++ b/src/string.c
@@ -5,6 +5,7 @@
 */
 
 #include <ctype.h>
+#include <float.h>
 #include <limits.h>
 #include <stddef.h>
 #include <stdlib.h>