diff --git a/src/admutils.c b/src/admutils.c
index dae3657..35a4427 100644
--- a/src/admutils.c
+++ b/src/admutils.c
@@ -537,7 +537,7 @@ testnan (double *a, int n)
   int i;
 
   for (i = 0; i < n; i++) {
-    if (!finite (a[i]))
+    if (!isfinite (a[i]))
       fatalx ("(testnan) fails:  index %d\n", i);
   }
 }