diff --git a/src/main.c b/src/main.c
index 23baa2b..b50ac93 100644
--- a/src/main.c
+++ b/src/main.c
@@ -16,6 +16,7 @@
 
 
 
+#include <sys/utsname.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -60,6 +61,7 @@ static int _usage(void)
 
 /* public */
 /* main */
+static int _main_default_defines(C99Prefs * prefs);
 static int _main_default_paths(C99Prefs * prefs);
 static int _main_add_define(C99Prefs * prefs, char * define);
 static int _main_add_path(C99Prefs * prefs, char const * path);
@@ -73,7 +75,8 @@ int main(int argc, char * argv[])
 	int o;
 
 	memset(&prefs, 0, sizeof(prefs));
-	if(_main_default_paths(&prefs) != 0)
+	if(_main_default_defines(&prefs) != 0
+			|| _main_default_paths(&prefs) != 0)
 		return 2;
 	while((o = getopt(argc, argv, "cD:EgI:L:m:M:o:O123sU:W")) != -1)
 		switch(o)
@@ -139,6 +142,23 @@ int main(int argc, char * argv[])
 	return (ret == 0) ? 0 : 2;
 }
 
+static int _main_default_defines(C99Prefs * prefs)
+	/* FIXME define these in the as plug-in instead */
+{
+	struct utsname uts;
+	static char sysname[sizeof(uts.sysname) + 7];
+	static char machine[sizeof(uts.machine) + 7];
+
+	if(uname(&uts) != 0)
+		return error_set_print(PACKAGE, 1, "%s", strerror(errno));
+	snprintf(sysname, sizeof(sysname), "__%s__=1", uts.sysname);
+	snprintf(machine, sizeof(machine), "__%s__=1", uts.machine);
+	if(_main_add_define(prefs, sysname) != 0
+			|| _main_add_define(prefs, machine) != 0)
+		return 1;
+	return 0;
+}
+
 static int _main_default_paths(C99Prefs * prefs)
 {
 	char * paths[] = { "/usr/include" };
@@ -163,6 +183,9 @@ static int _main_add_define(C99Prefs * prefs, char * define)
 	char ** p;
 	char * value;
 
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(\"%s\")\n", __func__, define);
+#endif
 	if(strlen(define) == 0)
 		return 1;
 	value = strtok(define, "=");
@@ -178,6 +201,9 @@ static int _main_add_path(C99Prefs * prefs, char const * path)
 {
 	const char ** p;
 
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(\"%s\")\n", __func__, path);
+#endif
 	if((p = realloc(prefs->paths, sizeof(*p) * (prefs->paths_cnt + 1)))
 			== NULL)
 		return error_set_print(PACKAGE, 1, "%s", strerror(errno));
@@ -190,6 +216,9 @@ static int _main_add_undefine(C99Prefs * prefs, char const * undefine)
 {
 	const char ** p;
 
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(\"%s\")\n", __func__, undefine);
+#endif
 	if(strlen(undefine) == 0)
 		return 1;
 	if((p = realloc(prefs->undefines, sizeof(*p)
@@ -205,6 +234,9 @@ static int _main_add_option(C99Prefs * prefs, char const * option)
 	C99Option * p;
 	char * q;
 
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(\"%s\")\n", __func__, option);
+#endif
 	if(strlen(option) == 0)
 		return 1;
 	if((p = realloc(prefs->options, sizeof(*p)