diff --git a/test/contour.c b/test/contour.c
index ad113882c..ea7bddd24 100644
--- a/test/contour.c
+++ b/test/contour.c
@@ -11,15 +11,16 @@
 #include "magics_api.h"
 #include <stdio.h>
 
+#define NUM_FORMATS 3
+
 int main()
 {
     mag_open();
-    const int num_formats = 3;
-    const char *formats[num_formats];
+    const char *formats[NUM_FORMATS];
     formats[0] = "ps";
     formats[1] = "png";
     formats[2] = "pdf";
-    mag_set1c("output_formats",formats,num_formats);
+    mag_set1c("output_formats",formats,NUM_FORMATS);
     mag_setc("output_name","contour"); // which is different each time
 
     /* load the data */