diff --git a/puma/src/user_eval.c b/puma/src/user_eval.c
index f531d0b..ac948ca 100644
--- a/puma/src/user_eval.c
+++ b/puma/src/user_eval.c
@@ -66,7 +66,7 @@ void user_eval(DDOUBLE xvar[],IINTEGER mode) {
     #undef   X
     #include "o8cons.h"
     
-    void    eval_extern(IINTEGER mode);
+    extern void (*eval_extern)(IINTEGER mode);
     DDOUBLE* d1_malloc(IINTEGER size1, IINTEGER init); 
 
     static DDOUBLE   *fusave,xhelp,xincr,sd1,sd2,sd3,d1,d2,d3;