diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index cabdc55e09..01dea59f58 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -742,7 +742,7 @@ static int run_and_feed_hook(const char *hook_name, feed_fn feed,
 		size_t n;
 		if (feed(feed_state, &buf, &n))
 			break;
-		if (write_in_full(proc.in, buf, n) != n)
+		if (write_in_full(proc.in, buf, n) < 0)
 			break;
 	}
 	close(proc.in);
diff --git a/builtin/rerere.c b/builtin/rerere.c
index ffb66e2907..0bc40298c2 100644
--- a/builtin/rerere.c
+++ b/builtin/rerere.c
@@ -18,7 +18,7 @@ static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
 {
 	int i;
 	for (i = 0; i < nbuf; i++)
-		if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
+		if (write_in_full(1, ptr[i].ptr, ptr[i].size) < 0)
 			return -1;
 	return 0;
 }
diff --git a/builtin/unpack-file.c b/builtin/unpack-file.c
index 73f1334191..672a54fcdf 100644
--- a/builtin/unpack-file.c
+++ b/builtin/unpack-file.c
@@ -15,7 +15,7 @@ static char *create_temp_file(unsigned char *sha1)
 
 	xsnprintf(path, sizeof(path), ".merge_file_XXXXXX");
 	fd = xmkstemp(path);
-	if (write_in_full(fd, buf, size) != size)
+	if (write_in_full(fd, buf, size) < 0)
 		die_errno("unable to write temp-file");
 	close(fd);
 	return path;
diff --git a/config.c b/config.c
index 6219086a2b..90b699575b 100644
--- a/config.c
+++ b/config.c
@@ -2565,7 +2565,7 @@ int git_config_set_multivar_in_file_gently(const char *config_filename,
 						  copy_end - copy_begin) < 0)
 					goto write_err_out;
 				if (new_line &&
-				    write_str_in_full(fd, "\n") != 1)
+				    write_str_in_full(fd, "\n") < 0)
 					goto write_err_out;
 			}
 			copy_begin = store.offset[i];
@@ -2796,7 +2796,7 @@ int git_config_rename_section_in_file(const char *config_filename,
 		if (remove)
 			continue;
 		length = strlen(output);
-		if (write_in_full(out_fd, output, length) != length) {
+		if (write_in_full(out_fd, output, length) < 0) {
 			ret = write_error(get_lock_file_path(lock));
 			goto out;
 		}
diff --git a/diff.c b/diff.c
index 9c38258030..6f58bca2f9 100644
--- a/diff.c
+++ b/diff.c
@@ -2975,7 +2975,7 @@ static void prep_temp_blob(const char *path, struct diff_tempfile *temp,
 		blob = buf.buf;
 		size = buf.len;
 	}
-	if (write_in_full(fd, blob, size) != size)
+	if (write_in_full(fd, blob, size) < 0)
 		die_errno("unable to write temp-file");
 	close_tempfile(&temp->tempfile);
 	temp->name = get_tempfile_path(&temp->tempfile);
diff --git a/fast-import.c b/fast-import.c
index a959161b46..395524039b 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -2951,7 +2951,7 @@ static void parse_reset_branch(const char *arg)
 
 static void cat_blob_write(const char *buf, unsigned long size)
 {
-	if (write_in_full(cat_blob_fd, buf, size) != size)
+	if (write_in_full(cat_blob_fd, buf, size) < 0)
 		die_errno("Write to frontend failed");
 }
 
diff --git a/http-backend.c b/http-backend.c
index 519025d2c3..5daff8ccab 100644
--- a/http-backend.c
+++ b/http-backend.c
@@ -357,7 +357,7 @@ static void inflate_request(const char *prog_name, int out, int buffer_input)
 				die("zlib error inflating request, result %d", ret);
 
 			n = stream.total_out - cnt;
-			if (write_in_full(out, out_buf, n) != n)
+			if (write_in_full(out, out_buf, n) < 0)
 				die("%s aborted reading request", prog_name);
 			cnt += n;
 
@@ -378,7 +378,7 @@ static void copy_request(const char *prog_name, int out)
 	ssize_t n = read_request(0, &buf);
 	if (n < 0)
 		die_errno("error reading request body");
-	if (write_in_full(out, buf, n) != n)
+	if (write_in_full(out, buf, n) < 0)
 		die("%s aborted reading request", prog_name);
 	close(out);
 	free(buf);
diff --git a/ll-merge.c b/ll-merge.c
index 9fb855a900..a6ad2ec12d 100644
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -154,7 +154,7 @@ static void create_temp(mmfile_t *src, char *path, size_t len)
 
 	xsnprintf(path, len, ".merge_file_XXXXXX");
 	fd = xmkstemp(path);
-	if (write_in_full(fd, src->ptr, src->size) != src->size)
+	if (write_in_full(fd, src->ptr, src->size) < 0)
 		die_errno("unable to write temp-file");
 	close(fd);
 }
diff --git a/read-cache.c b/read-cache.c
index acfb028f48..5e6d24d444 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1921,7 +1921,7 @@ static int ce_write_flush(git_SHA_CTX *context, int fd)
 	unsigned int buffered = write_buffer_len;
 	if (buffered) {
 		git_SHA1_Update(context, write_buffer, buffered);
-		if (write_in_full(fd, write_buffer, buffered) != buffered)
+		if (write_in_full(fd, write_buffer, buffered) < 0)
 			return -1;
 		write_buffer_len = 0;
 	}
@@ -1970,7 +1970,7 @@ static int ce_flush(git_SHA_CTX *context, int fd, unsigned char *sha1)
 
 	/* Flush first if not enough space for SHA1 signature */
 	if (left + 20 > WRITE_BUFFER_SIZE) {
-		if (write_in_full(fd, write_buffer, left) != left)
+		if (write_in_full(fd, write_buffer, left) < 0)
 			return -1;
 		left = 0;
 	}
@@ -1979,7 +1979,7 @@ static int ce_flush(git_SHA_CTX *context, int fd, unsigned char *sha1)
 	git_SHA1_Final(write_buffer + left, context);
 	hashcpy(sha1, write_buffer + left);
 	left += 20;
-	return (write_in_full(fd, write_buffer, left) != left) ? -1 : 0;
+	return (write_in_full(fd, write_buffer, left) < 0) ? -1 : 0;
 }
 
 static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
diff --git a/refs.c b/refs.c
index ea2b9f84f8..a5abca04b7 100644
--- a/refs.c
+++ b/refs.c
@@ -592,7 +592,7 @@ static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 		}
 	}
 
-	if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
+	if (write_in_full(fd, buf.buf, buf.len) < 0) {
 		strbuf_addf(err, "could not write to '%s'", filename);
 		rollback_lock_file(&lock);
 		goto done;
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 0404f2c233..924e8537f3 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2118,8 +2118,8 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
 		return -1;
 	}
 	fd = get_lock_file_fd(lock->lk);
-	if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
-	    write_in_full(fd, &term, 1) != 1 ||
+	if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) < 0 ||
+	    write_in_full(fd, &term, 1) < 0 ||
 	    close_ref(lock) < 0) {
 		strbuf_addf(err,
 			    "couldn't write '%s'", get_lock_file_path(lock->lk));
@@ -3338,8 +3338,8 @@ static int files_reflog_expire(struct ref_store *ref_store,
 					strerror(errno));
 		} else if (update &&
 			   (write_in_full(get_lock_file_fd(lock->lk),
-				oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
-			    write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
+				oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) < 0 ||
+			    write_str_in_full(get_lock_file_fd(lock->lk), "\n") < 0 ||
 			    close_ref(lock) < 0)) {
 			status |= error("couldn't write %s",
 					get_lock_file_path(lock->lk));
diff --git a/rerere.c b/rerere.c
index 70634d456c..51376cf6da 100644
--- a/rerere.c
+++ b/rerere.c
@@ -258,7 +258,7 @@ static int write_rr(struct string_list *rr, int out_fd)
 				    rerere_id_hex(id),
 				    rr->items[i].string, 0);
 
-		if (write_in_full(out_fd, buf.buf, buf.len) != buf.len)
+		if (write_in_full(out_fd, buf.buf, buf.len) < 0)
 			die("unable to write rerere record");
 
 		strbuf_release(&buf);
diff --git a/shallow.c b/shallow.c
index 54359d5490..e8429a9a84 100644
--- a/shallow.c
+++ b/shallow.c
@@ -296,7 +296,7 @@ const char *setup_temporary_shallow(const struct oid_array *extra)
 	if (write_shallow_commits(&sb, 0, extra)) {
 		fd = xmks_tempfile(&temporary_shallow, git_path("shallow_XXXXXX"));
 
-		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
+		if (write_in_full(fd, sb.buf, sb.len) < 0)
 			die_errno("failed to write to %s",
 				  get_tempfile_path(&temporary_shallow));
 		close_tempfile(&temporary_shallow);
@@ -321,7 +321,7 @@ void setup_alternate_shallow(struct lock_file *shallow_lock,
 				       LOCK_DIE_ON_ERROR);
 	check_shallow_file_for_update();
 	if (write_shallow_commits(&sb, 0, extra)) {
-		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
+		if (write_in_full(fd, sb.buf, sb.len) < 0)
 			die_errno("failed to write to %s",
 				  get_lock_file_path(shallow_lock));
 		*alternate_shallow_file = get_lock_file_path(shallow_lock);
@@ -368,7 +368,7 @@ void prune_shallow(int show_only)
 				       LOCK_DIE_ON_ERROR);
 	check_shallow_file_for_update();
 	if (write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY)) {
-		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
+		if (write_in_full(fd, sb.buf, sb.len) < 0)
 			die_errno("failed to write to %s",
 				  get_lock_file_path(&shallow_lock));
 		commit_lock_file(&shallow_lock);
diff --git a/t/helper/test-delta.c b/t/helper/test-delta.c
index 59937dc1be..591730adc4 100644
--- a/t/helper/test-delta.c
+++ b/t/helper/test-delta.c
@@ -69,7 +69,7 @@ int cmd_main(int argc, const char **argv)
 	}
 
 	fd = open (argv[4], O_WRONLY|O_CREAT|O_TRUNC, 0666);
-	if (fd < 0 || write_in_full(fd, out_buf, out_size) != out_size) {
+	if (fd < 0 || write_in_full(fd, out_buf, out_size) < 0) {
 		perror(argv[4]);
 		return 1;
 	}
diff --git a/transport-helper.c b/transport-helper.c
index 33cff38cc0..2128a32f1c 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -44,8 +44,7 @@ static void sendline(struct helper_data *helper, struct strbuf *buffer)
 {
 	if (debug)
 		fprintf(stderr, "Debug: Remote helper: -> %s", buffer->buf);
-	if (write_in_full(helper->helper->in, buffer->buf, buffer->len)
-		!= buffer->len)
+	if (write_in_full(helper->helper->in, buffer->buf, buffer->len) < 0)
 		die_errno("Full write to remote helper failed");
 }
 
@@ -74,7 +73,7 @@ static void write_constant(int fd, const char *str)
 {
 	if (debug)
 		fprintf(stderr, "Debug: Remote helper: -> %s", str);
-	if (write_in_full(fd, str, strlen(str)) != strlen(str))
+	if (write_in_full(fd, str, strlen(str)) < 0)
 		die_errno("Full write to remote helper failed");
 }
 
diff --git a/wrapper.c b/wrapper.c
index 36630e5d18..61aba0b5c1 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -652,7 +652,7 @@ int xsnprintf(char *dst, size_t max, const char *fmt, ...)
 void write_file_buf(const char *path, const char *buf, size_t len)
 {
 	int fd = xopen(path, O_WRONLY | O_CREAT | O_TRUNC, 0666);
-	if (write_in_full(fd, buf, len) != len)
+	if (write_in_full(fd, buf, len) < 0)
 		die_errno(_("could not write to %s"), path);
 	if (close(fd))
 		die_errno(_("could not close %s"), path);