diff --git a/qpkg/id.h b/qpkg/id.h
index 0614266..ab4f78e 100644
--- a/qpkg/id.h
+++ b/qpkg/id.h
@@ -59,6 +59,14 @@ struct id {
 };
 
 
+/*
+ * Helper macro for printing identifiers.
+ * Use with "... %.*s ..."
+ */
+
+#define	ID2PF(id)	(int) (id)->len, (id)->s
+
+
 int comp_id(const void *a, const void *b);
 
 struct tree *make_tree(int (*comp)(const void *a, const void *b));
diff --git a/qpkg/prereq.c b/qpkg/prereq.c
index 05a7bdc..b12f2d6 100644
--- a/qpkg/prereq.c
+++ b/qpkg/prereq.c
@@ -36,9 +36,6 @@ static int n_stack = 0;
 static int stack_max = 0;
 
 
-#define ID2S(id) (int) (id)->len, (id)->s
-
-
 static int epoch(const char **s, const struct id *id)
 {
 	const char *end = id->s+id->len;
@@ -114,7 +111,7 @@ static void done(void)
 
 static void push(struct pkg *pkg)
 {
-//fprintf(stderr, "push %.*s\n", ID2S(pkg->id));
+//fprintf(stderr, "push %.*s\n", ID2PF(pkg->id));
 	if (n_stack == stack_max) {
 		stack_max = (stack_max+1)*2;
 		stack = realloc(stack, sizeof(*stack)*stack_max);
@@ -149,7 +146,7 @@ static int satisfies(const struct pkg *pkg, const struct ref *ref)
 	assert(pkg->version);
 	cmp = comp_versions(pkg->version, ref->version);
 //fprintf(stderr, "%.*s <%d> %.*s\n",
-//  ID2S(pkg->version), cmp, ID2S(ref->version));
+//  ID2PF(pkg->version), cmp, ID2PF(ref->version));
 	switch (ref->relop) {
 	case rel_eq:
 		return !cmp;
@@ -193,9 +190,9 @@ static int level = 0;
 			return;
 #if 0
 fprintf(stderr, "%*s", level, "");
-fprintf(stderr, "%.*s %p", ID2S(pkg->id), pkg);
+fprintf(stderr, "%.*s %p", ID2PF(pkg->id), pkg);
 if (pkg->version)
-fprintf(stderr, " %.*s", ID2S(pkg->version));
+fprintf(stderr, " %.*s", ID2PF(pkg->version));
 if (pkg->mark) fprintf(stderr, " +");
 if (pkg->flags & QPKG_INSTALLED) fprintf(stderr, " ***");
 fprintf(stderr, "\n");