Index: uspace/lib/libc/generic/io/io.c
===================================================================
--- uspace/lib/libc/generic/io/io.c	(revision 2a5af223633736d7b866a2f1a951142fe72dc78b)
+++ uspace/lib/libc/generic/io/io.c	(revision 216cb85316fa347aa65efa528359fb202c2fdd80)
@@ -341,9 +341,14 @@
 size_t fread(void *buf, size_t size, size_t nmemb, FILE *stream)
 {
-	size_t left = size * nmemb;
-	size_t done = 0;
-	
+	size_t left, done;
+
+	if (size == 0 || nmemb == 0)
+		return 0;
+
 	/* Make sure no data is pending write. */
 	_fflushbuf(stream);
+
+	left = size * nmemb;
+	done = 0;
 	
 	while ((left > 0) && (!stream->error) && (!stream->eof)) {
@@ -365,7 +370,13 @@
 static size_t _fwrite(const void *buf, size_t size, size_t nmemb, FILE *stream)
 {
-	size_t left = size * nmemb;
-	size_t done = 0;
-	
+	size_t left;
+	size_t done;
+
+	if (size == 0 || nmemb == 0)
+		return 0;
+
+	left = size * nmemb;
+	done = 0;
+
 	while ((left > 0) && (!stream->error)) {
 		ssize_t wr;
@@ -421,5 +432,8 @@
 	uint8_t b;
 	bool need_flush;
-	
+
+	if (size == 0 || nmemb == 0)
+		return 0;
+
 	/* If not buffered stream, write out directly. */
 	if (stream->btype == _IONBF) {