diff --git a/src/ulong_extras/is_square.c b/src/ulong_extras/is_square.c
index 8ffe61964e..322bde868d 100644
--- a/src/ulong_extras/is_square.c
+++ b/src/ulong_extras/is_square.c
@@ -12,15 +12,15 @@
 #include <math.h>
 #include "ulong_extras.h"
 
-int mod64[64] = {1,1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,1,0,0,0,
+static int mod64[64] = {1,1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,1,0,0,0,
                  0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,1,
                  0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0};
 
-int mod65[65] = {1,1,0,0,1,0,0,0,0,1,1,0,0,0,1,0,1,0,0,0,0,0,
+static int mod65[65] = {1,1,0,0,1,0,0,0,0,1,1,0,0,0,1,0,1,0,0,0,0,0,
                  0,0,0,1,1,0,0,1,1,0,0,0,0,1,1,0,0,1,1,0,0,0,
                  0,0,0,0,0,1,0,1,0,0,0,1,1,0,0,0,0,1,0,0,1};
 
-int mod63[63] = {1,1,0,0,1,0,0,1,0,1,0,0,0,0,1,0,1,0,1,0,0,
+static int mod63[63] = {1,1,0,0,1,0,0,1,0,1,0,0,0,0,1,0,1,0,1,0,0,
                  0,1,0,0,1,0,0,1,0,0,0,0,0,0,1,1,1,0,0,0,0,
                  0,1,0,0,1,0,0,1,0,0,0,0,0,0,1,0,1,0,0,0,0};