diff --git a/STATUS b/STATUS
index c617b0b..5f0899a 100644
--- a/STATUS
+++ b/STATUS
@@ -91,13 +91,13 @@ TEST:       Function/symbol/macro needs to be tested
      7.19.4.3  tmpfile                       TODO
      7.19.4.4  tmpnam                        TODO
 
-     7.19.5.1  fclose                        TEST
-     7.19.5.2  fflush                        TEST
-     7.19.5.3  fopen                         TEST
+     7.19.5.1  fclose                        -
+     7.19.5.2  fflush                        -
+     7.19.5.3  fopen                         TEST ("a" and "+" modes remain)
      (EXT)     fdopen                        TEST
      7.19.5.4  freopen                       TEST
-     7.19.5.5  setbuf                        TEST
-     7.19.5.6  setvbuf                       TEST
+     7.19.5.5  setbuf                        -
+     7.19.5.6  setvbuf                       -
 
      7.19.6.1  fprintf                       LDEPS(fwrite)
      7.19.6.2  fscanf                        TODO
@@ -130,14 +130,14 @@ TEST:       Function/symbol/macro needs to be tested
      7.19.7.10 puts                          LDEPS(fputs)
      7.19.7.11 ungetc                        TODO
 
-     7.19.8.1  fread                         TEST
-     7.19.8.2  fwrite                        TEST
+     7.19.8.1  fread                         TEST ("a" and "+" modes remain)
+     7.19.8.2  fwrite                        TEST ("a" and "+" modes remain)
 
-     7.19.9.1  fgetpos                       TEST
-     7.19.9.2  fseek                         TEST
-     7.19.9.3  fsetpos                       TEST
-     7.19.9.4  ftell                         TEST
-     7.19.9.5  rewind                        TEST
+     7.19.9.1  fgetpos                       -
+     7.19.9.2  fseek                         -
+     7.19.9.3  fsetpos                       -
+     7.19.9.4  ftell                         -
+     7.19.9.5  rewind                        -
 
      7.19.10.1 clearerr                      -
      7.19.10.2 feof                          -
diff --git a/src/libc/stdio/fileutil.c b/src/libc/stdio/fileutil.c
index 4afe624..a55de18 100644
--- a/src/libc/stdio/fileutil.c
+++ b/src/libc/stdio/fileutil.c
@@ -77,6 +77,12 @@ ssize_t __fp_write(FILE *fp, void const *data, size_t size)
 {
 	size_t written = 0;
 
+	if(fp->append) {
+		int rc = fseek(fp, 0, SEEK_END);
+		if(rc < 0)
+			return EOF;
+	}
+
 	while(written < size) {
 		ssize_t rc = write(fp->fd, data + written, size - written);
 
diff --git a/src/libc/stdio/fread.c b/src/libc/stdio/fread.c
index e8bc584..053136c 100644
--- a/src/libc/stdio/fread.c
+++ b/src/libc/stdio/fread.c
@@ -4,6 +4,11 @@
 
 size_t fread(void *data, size_t membsize, size_t nmemb, FILE *fp)
 {
+	if(!fp->readable) {
+		fp->error = 1;
+		return 0;
+	}
+
 	size_t size;
 	if(__builtin_umul_overflow(membsize, nmemb, &size)) {
 		fp->error = 1;
diff --git a/src/libc/stdio/fsetpos.c b/src/libc/stdio/fsetpos.c
index ffaa4e0..b1cbdcb 100644
--- a/src/libc/stdio/fsetpos.c
+++ b/src/libc/stdio/fsetpos.c
@@ -6,7 +6,10 @@ int fsetpos(FILE *fp, fpos_t const *pos)
 	if(fflush(fp) == EOF)
 		return -1;
 
-	lseek(fp->fd, *pos, SEEK_SET);
+	off_t rc = lseek(fp->fd, *pos, SEEK_SET);
+	if(rc < 0)
+		return -1;
+
 	fp->fdpos = *pos;
 	fp->eof = 0;
 	return 0;
diff --git a/src/libc/stdio/fwrite.c b/src/libc/stdio/fwrite.c
index 065949d..fd9f33b 100644
--- a/src/libc/stdio/fwrite.c
+++ b/src/libc/stdio/fwrite.c
@@ -4,6 +4,11 @@
 
 size_t fwrite(void const *data, size_t membsize, size_t nmemb, FILE *fp)
 {
+	if(!fp->writable) {
+		fp->error = 1;
+		return 0;
+	}
+
 	size_t size;
 	if(__builtin_umul_overflow(membsize, nmemb, &size)) {
 		fp->error = 1;
@@ -17,20 +22,29 @@ size_t fwrite(void const *data, size_t membsize, size_t nmemb, FILE *fp)
 
 	__fp_buffer_mode_write(fp);
 
-	// TODO: fwrite: line buffering
-
 	size_t size_written = 0;
+
 	while(size_written < size) {
-		/* Fill the buffer */
 		size_t size_frag = fp->bufsize - fp->bufpos;
-		if(size_frag > size - size_written)
+		void const *last_line = NULL;
+
+		if(size_frag >= size - size_written) {
 			size_frag = size - size_written;
 
+			/* In the last run, if line buffering is enabled and
+			   there is a newline, stop at that newline and flush
+			   before the last write to buffer */
+			if(fp->bufmode == _IOLBF) last_line = memrchr(
+				data + size_written, '\n', size_frag);
+		}
+		if(last_line)
+			size_frag = (last_line + 1) - (data + size_written);
+
 		memcpy(fp->buf + fp->bufpos, data + size_written, size_frag);
 		size_written += size_frag;
 		fp->bufpos += size_frag;
 
-		if(fp->bufpos >= fp->bufsize) {
+		if(fp->bufpos >= fp->bufsize || last_line) {
 			ssize_t rc = __fp_write(fp, fp->buf, fp->bufpos);
 			if(rc <= 0) /* error */
 				break;