diff --git a/libpkgconf/libpkgconf.h b/libpkgconf/libpkgconf.h
index c55d1b2..c191f7f 100644
--- a/libpkgconf/libpkgconf.h
+++ b/libpkgconf/libpkgconf.h
@@ -128,8 +128,23 @@ struct pkgconf_pkg_ {
 typedef void (*pkgconf_pkg_iteration_func_t)(const pkgconf_pkg_t *pkg);
 typedef void (*pkgconf_pkg_traverse_func_t)(pkgconf_pkg_t *pkg, void *data, unsigned int flags);
 typedef bool (*pkgconf_queue_apply_func_t)(pkgconf_pkg_t *world, void *data, int maxdepth, unsigned int flags);
+typedef bool (*pkgconf_error_handler_func_t)(const char *msg);
 
 /* pkg.c */
+#if defined(__GNUC__) || defined(__INTEL_COMPILER)
+#define PRINTFLIKE(fmtarg, firstvararg) \
+        __attribute__((__format__ (__printf__, fmtarg, firstvararg)))
+#define DEPRECATED \
+        __attribute__((deprecated))
+#else
+#define PRINTFLIKE(fmtarg, firstvararg)
+#define DEPRECATED
+#endif /* defined(__INTEL_COMPILER) || defined(__GNUC__) */
+
+bool pkgconf_error(const char *format, ...) PRINTFLIKE(1, 2);
+bool pkgconf_default_error_handler(const char *msg);
+void pkgconf_set_error_handler(pkgconf_error_handler_func_t func);
+
 pkgconf_pkg_t *pkgconf_pkg_ref(pkgconf_pkg_t *pkg);
 void pkgconf_pkg_unref(pkgconf_pkg_t *pkg);
 void pkgconf_pkg_free(pkgconf_pkg_t *pkg);
@@ -176,9 +191,6 @@ char *pkgconf_tuple_find_global(const char *key);
 void pkgconf_tuple_free_global(void);
 void pkgconf_tuple_define_global(const char *kv);
 
-/* main.c */
-extern FILE *error_msgout;
-
 /* queue.c */
 void pkgconf_queue_push(pkgconf_list_t *list, const char *package);
 bool pkgconf_queue_compile(pkgconf_pkg_t *world, pkgconf_list_t *list);
diff --git a/libpkgconf/pkg.c b/libpkgconf/pkg.c
index 9abe524..48bf76b 100644
--- a/libpkgconf/pkg.c
+++ b/libpkgconf/pkg.c
@@ -15,6 +15,35 @@
 
 #include <libpkgconf/libpkgconf.h>
 
+static pkgconf_error_handler_func_t pkgconf_error_handler = pkgconf_default_error_handler;
+
+bool
+pkgconf_error(const char *format, ...)
+{
+	char errbuf[PKGCONF_BUFSIZE];
+	va_list va;
+
+	va_start(va, format);
+	vsnprintf(errbuf, sizeof errbuf, format, va);
+	va_end(va);
+
+	return pkgconf_error_handler(errbuf);
+}
+
+bool
+pkgconf_default_error_handler(const char *msg)
+{
+	(void) msg;
+
+	return true;
+}
+
+void
+pkgconf_set_error_handler(pkgconf_error_handler_func_t func)
+{
+	pkgconf_error_handler = func;
+}
+
 #ifdef _WIN32
 #	define PKG_CONFIG_REG_KEY "Software\\pkgconfig\\PKG_CONFIG_PATH"
 #	undef PKG_DEFAULT_PATH
@@ -802,21 +831,21 @@ pkgconf_pkg_report_graph_error(pkgconf_pkg_t *parent, pkgconf_pkg_t *pkg, pkgcon
 	{
 		if (!already_sent_notice)
 		{
-			fprintf(error_msgout, "Package %s was not found in the pkg-config search path.\n", node->package);
-			fprintf(error_msgout, "Perhaps you should add the directory containing `%s.pc'\n", node->package);
-			fprintf(error_msgout, "to the PKG_CONFIG_PATH environment variable\n");
+			pkgconf_error("Package %s was not found in the pkg-config search path.\n", node->package);
+			pkgconf_error("Perhaps you should add the directory containing `%s.pc'\n", node->package);
+			pkgconf_error("to the PKG_CONFIG_PATH environment variable\n");
 			already_sent_notice = true;
 		}
 
-		fprintf(error_msgout, "Package '%s', required by '%s', not found\n", node->package, parent->id);
+		pkgconf_error("Package '%s', required by '%s', not found\n", node->package, parent->id);
 	}
 	else if (eflags & PKGCONF_PKG_ERRF_PACKAGE_VER_MISMATCH)
 	{
-		fprintf(error_msgout, "Package dependency requirement '%s %s %s' could not be satisfied.\n",
+		pkgconf_error("Package dependency requirement '%s %s %s' could not be satisfied.\n",
 			node->package, pkgconf_pkg_get_comparator(node), node->version);
 
 		if (pkg != NULL)
-			fprintf(error_msgout, "Package '%s' has version '%s', required version is '%s %s'\n",
+			pkgconf_error("Package '%s' has version '%s', required version is '%s %s'\n",
 				node->package, pkg->version, pkgconf_pkg_get_comparator(node), node->version);
 	}
 
@@ -896,11 +925,11 @@ pkgconf_pkg_walk_conflicts_list(pkgconf_pkg_t *root, pkgconf_list_t *deplist, un
 			pkgdep = pkgconf_pkg_verify_dependency(parentnode, flags, &eflags);
 			if (eflags == PKGCONF_PKG_ERRF_OK)
 			{
-				fprintf(error_msgout, "Version '%s' of '%s' conflicts with '%s' due to satisfying conflict rule '%s %s%s%s'.\n",
+				pkgconf_error("Version '%s' of '%s' conflicts with '%s' due to satisfying conflict rule '%s %s%s%s'.\n",
 					pkgdep->version, pkgdep->realname, root->realname, parentnode->package, pkgconf_pkg_get_comparator(parentnode),
 					parentnode->version != NULL ? " " : "", parentnode->version != NULL ? parentnode->version : "");
-				fprintf(error_msgout, "It may be possible to ignore this conflict and continue, try the\n");
-				fprintf(error_msgout, "PKG_CONFIG_IGNORE_CONFLICTS environment variable.\n");
+				pkgconf_error("It may be possible to ignore this conflict and continue, try the\n");
+				pkgconf_error("PKG_CONFIG_IGNORE_CONFLICTS environment variable.\n");
 
 				pkgconf_pkg_unref(pkgdep);
 
diff --git a/libpkgconf/stdinc.h b/libpkgconf/stdinc.h
index c892ebd..b2fba50 100644
--- a/libpkgconf/stdinc.h
+++ b/libpkgconf/stdinc.h
@@ -21,6 +21,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
+#include <stdarg.h>
 #include <string.h>
 #include <dirent.h>
 #include <sys/types.h>
diff --git a/main.c b/main.c
index d835563..da51a19 100644
--- a/main.c
+++ b/main.c
@@ -58,6 +58,13 @@ static char *sysroot_dir = NULL;
 
 FILE *error_msgout = NULL;
 
+static bool
+error_handler(const char *msg)
+{
+	fprintf(error_msgout, "%s", msg);
+	return true;
+}
+
 static bool
 fragment_has_system_dir(pkgconf_fragment_t *frag)
 {
@@ -691,6 +698,8 @@ main(int argc, char *argv[])
 		return EXIT_SUCCESS;
 	}
 
+	pkgconf_set_error_handler(error_handler);
+
 	error_msgout = stderr;
 	if ((want_flags & PKG_ERRORS_ON_STDOUT) == PKG_ERRORS_ON_STDOUT)
 		error_msgout = stdout;