diff --git a/plugins/network/if1sec-c.c b/plugins/network/if1sec-c.c
index 47f7842d..b7ec5bfc 100644
--- a/plugins/network/if1sec-c.c
+++ b/plugins/network/if1sec-c.c
@@ -38,8 +38,8 @@ char* get_ifname_from_procstatline(char* line) {
 
 int config() {
 	/* Get the number of if */
-	int f;
-	if ( !(f=open(PROC_STAT, O_RDONLY)) ) {
+	int f = open(PROC_STAT, O_RDONLY);
+	if ( f == -1 ) {
 		return fail("cannot open " PROC_STAT);
 	}
 
@@ -120,7 +120,7 @@ int acquire() {
 	/* fork ourselves if not asked otherwise */
 	char* no_fork = getenv("no_fork");
 	if (! no_fork || strcmp("1", no_fork)) {
-		if (fork()) return;
+		if (fork()) return 0;
 		// we are the child, complete the daemonization
 
 		/* Close standard IO */
@@ -139,9 +139,15 @@ int acquire() {
 
 	/* Reading /proc/stat */
 	int f = open(PROC_STAT, O_RDONLY);
+	if ( f == -1 ) {
+		return fail("cannot open " PROC_STAT);
+	}
 
 	/* open the spoolfile */
 	int cache_file = open(cache_filename, O_CREAT | O_APPEND | O_WRONLY, S_IRUSR | S_IWUSR);
+	if ( cache_file == -1 ) {
+		return fail("cannot open the spoolfile");
+	}
 
 	/* loop each second */
 	while (1) {
@@ -213,6 +219,9 @@ int acquire() {
 
 int fetch() {
 	FILE* cache_file = fopen(cache_filename, "r+");
+	if ( !cache_file ) {
+		return fail("cannot open cache file");
+	}
 
 	/* lock */
 	flock(fileno(cache_file), LOCK_EX);