diff --git a/include/tradstdc.h b/include/tradstdc.h
index d77348f85..3681861aa 100644
--- a/include/tradstdc.h
+++ b/include/tradstdc.h
@@ -401,6 +401,9 @@ typedef genericptr genericptr_t; /* (void *) or (char *) */
 #if (__GNUC__ >= 2) && !defined(USE_OLDARGS)
 #define PRINTF_F(f, v) __attribute__((format(printf, f, v)))
 #endif
+#if (__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)
+#define PRINTF_F_PTR(f, v) PRINTF_F(f, v)
+#endif
 #if __GNUC__ >= 3
 #define UNUSED __attribute__((unused))
 #define NORETURN __attribute__((noreturn))
@@ -419,6 +422,9 @@ typedef genericptr genericptr_t; /* (void *) or (char *) */
 #ifndef PRINTF_F
 #define PRINTF_F(f, v)
 #endif
+#ifndef PRINTF_F_PTR
+#define PRINTF_F_PTR(f, v)
+#endif
 #ifndef UNUSED
 #define UNUSED
 #endif
diff --git a/src/mkobj.c b/src/mkobj.c
index 53f5cf64f..8f3893c89 100644
--- a/src/mkobj.c
+++ b/src/mkobj.c
@@ -761,7 +761,7 @@ static const char dknowns[] = { WAND_CLASS,   RING_CLASS, POTION_CLASS,
 void
 clear_dknown(struct obj *obj)
 {
-    obj->dknown = strchr(dknowns, obj->oclass) ? 0 : 1;
+    obj->dknown = index(dknowns, obj->oclass) ? 0 : 1;
     if ((obj->otyp >= ELVEN_SHIELD && obj->otyp <= ORCISH_SHIELD)
         || obj->otyp == SHIELD_OF_REFLECTION
         || objects[obj->otyp].oc_merge)
@@ -2107,7 +2107,7 @@ place_object(struct obj *otmp, coordxy x, coordxy y)
     register struct obj *otmp2;
 
     if (!isok(x, y)) { /* validate location */
-        void (*func)(const char *, ...) PRINTF_F(1, 2);
+        void (*func)(const char *, ...) PRINTF_F_PTR(1, 2);
 
         func = (x < 0 || y < 0 || x > COLNO - 1 || y > ROWNO - 1) ? panic
                : impossible;
diff --git a/src/vault.c b/src/vault.c
index f86a4b5e2..18db9adc0 100644
--- a/src/vault.c
+++ b/src/vault.c
@@ -413,7 +413,7 @@ invault(void)
            otherwise the hero wouldn't be able to push one to follow the
            guard out of the vault because that guard would be in its way */
         if ((otmp = sobj_at(BOULDER, guard->mx, guard->my)) != 0) {
-            void (*func)(const char *, ...) PRINTF_F(1, 2);
+            void (*func)(const char *, ...) PRINTF_F_PTR(1, 2);
             const char *bname = simpleonames(otmp);
             int bcnt = 0;