diff --git a/src/program.c b/src/program.c
index a0cf735ba1462370d3c1084c5f92579f2eae3d49..f3993f5602eb4bd006a77e83396301529688f8cb 100644
--- a/src/program.c
+++ b/src/program.c
@@ -5,7 +5,7 @@
 \*/
 /**/
 #include "global.h"
-RCSID("$Id: program.c,v 1.195 1999/12/31 14:51:42 grubba Exp $");
+RCSID("$Id: program.c,v 1.196 1999/12/31 15:40:47 grubba Exp $");
 #include "program.h"
 #include "object.h"
 #include "dynamic_buffer.h"
@@ -3740,7 +3740,7 @@ static struct implements_cache_s is_compatible_cache[IMPLEMENTS_CACHE_SIZE];
 /* Returns 1 if a is compatible with b
  * ie it's possible to write a hypothetical c that implements both.
  */
-int is_compatible(struct program *a, struct program b)
+int is_compatible(struct program *a, struct program *b)
 {
   unsigned long hval;
   unsigned long rhval;
diff --git a/src/program.h b/src/program.h
index b808b1bf9227c24dfc3b4e6f338265ece3990e19..798cf8d6ddbc03635898032b22735eea8362b60b 100644
--- a/src/program.h
+++ b/src/program.h
@@ -5,7 +5,7 @@
 \*/
 
 /*
- * $Id: program.h,v 1.76 1999/12/31 14:52:43 grubba Exp $
+ * $Id: program.h,v 1.77 1999/12/31 15:40:14 grubba Exp $
  */
 #ifndef PROGRAM_H
 #define PROGRAM_H
@@ -461,7 +461,7 @@ int find_child(struct program *parent, struct program *child);
 void yywarning(char *fmt, ...) ATTRIBUTE((format(printf,1,2)));
 struct implements_cache_s;
 int implements(struct program *a, struct program *b);
-int is_compatible(struct program *a, struct program b);
+int is_compatible(struct program *a, struct program *b);
 int yyexplain_not_implements(struct program *a, struct program *b);
 /* Prototypes end here */