diff --git a/src/bin/pg_rewind/copy_fetch.c b/src/bin/pg_rewind/copy_fetch.c
index 1ca00d12ad..991e348670 100644
--- a/src/bin/pg_rewind/copy_fetch.c
+++ b/src/bin/pg_rewind/copy_fetch.c
@@ -43,7 +43,7 @@ traverse_datadir(const char *datadir, process_file_callback_t callback)
 /*
  * recursive part of traverse_datadir
  *
- * parent_path is the current subdirectory's path relative to datadir,
+ * parentpath is the current subdirectory's path relative to datadir,
  * or NULL at the top level.
  */
 static void
@@ -262,5 +262,5 @@ execute_pagemap(datapagemap_t *pagemap, const char *path)
 		copy_file_range(path, offset, offset + BLCKSZ, false);
 		/* Ok, this block has now been copied from new data dir to old */
 	}
-	free(iter);
+	pg_free(iter);
 }
diff --git a/src/bin/pg_rewind/datapagemap.c b/src/bin/pg_rewind/datapagemap.c
index 3477366af9..ff10bc9653 100644
--- a/src/bin/pg_rewind/datapagemap.c
+++ b/src/bin/pg_rewind/datapagemap.c
@@ -67,7 +67,7 @@ datapagemap_add(datapagemap_t *map, BlockNumber blkno)
  * Start iterating through all entries in the page map.
  *
  * After datapagemap_iterate, call datapagemap_next to return the entries,
- * until it returns NULL. After you're done, use free() to destroy the
+ * until it returns false. After you're done, use pg_free() to destroy the
  * iterator.
  */
 datapagemap_iterator_t *
@@ -122,5 +122,5 @@ datapagemap_print(datapagemap_t *map)
 	while (datapagemap_next(iter, &blocknum))
 		printf("  blk %u\n", blocknum);
 
-	free(iter);
+	pg_free(iter);
 }
diff --git a/src/bin/pg_rewind/file_ops.c b/src/bin/pg_rewind/file_ops.c
index 589a01a434..d6a743f788 100644
--- a/src/bin/pg_rewind/file_ops.c
+++ b/src/bin/pg_rewind/file_ops.c
@@ -105,10 +105,16 @@ write_target_range(char *buf, off_t begin, size_t size)
 	{
 		int			writelen;
 
+		errno = 0;
 		writelen = write(dstfd, p, writeleft);
 		if (writelen < 0)
+		{
+			/* if write didn't set errno, assume problem is no disk space */
+			if (errno == 0)
+				errno = ENOSPC;
 			pg_fatal("could not write file \"%s\": %s\n",
 					 dstpath, strerror(errno));
+		}
 
 		p += writelen;
 		writeleft -= writelen;
diff --git a/src/bin/pg_rewind/filemap.c b/src/bin/pg_rewind/filemap.c
index cb2bf4d1a0..3821e9c846 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -114,7 +114,7 @@ process_source_file(const char *path, file_type_t type, size_t newsize,
 		case FILE_TYPE_DIRECTORY:
 			if (exists && !S_ISDIR(statbuf.st_mode))
 			{
-				/* it's a directory in target, but not in source. Strange.. */
+				/* it's a directory in source, but not in target. Strange.. */
 				pg_fatal("\"%s\" is not a directory\n", localpath);
 			}
 
@@ -135,7 +135,7 @@ process_source_file(const char *path, file_type_t type, size_t newsize,
 				)
 			{
 				/*
-				 * It's a symbolic link in target, but not in source.
+				 * It's a symbolic link in source, but not in target.
 				 * Strange..
 				 */
 				pg_fatal("\"%s\" is not a symbolic link\n", localpath);
@@ -354,7 +354,7 @@ process_block_change(ForkNumber forknum, RelFileNode rnode, BlockNumber blkno)
 		entry = *e;
 	else
 		entry = NULL;
-	free(path);
+	pfree(path);
 
 	if (entry)
 	{
@@ -530,7 +530,7 @@ print_filemap(void)
  * Does it look like a relation data file?
  *
  * For our purposes, only files belonging to the main fork are considered
- * relation files. Other forks are alwayes copied in toto, because we cannot
+ * relation files. Other forks are always copied in toto, because we cannot
  * reliably track changes to them, because WAL only contains block references
  * for the main fork.
  */
diff --git a/src/bin/pg_rewind/libpq_fetch.c b/src/bin/pg_rewind/libpq_fetch.c
index 14a861006d..6ffd24e9f1 100644
--- a/src/bin/pg_rewind/libpq_fetch.c
+++ b/src/bin/pg_rewind/libpq_fetch.c
@@ -69,7 +69,7 @@ libpqConnect(const char *connstr)
 	pg_free(str);
 
 	/*
-	 * Also check that full_page-writes are enabled. We can get torn pages if
+	 * Also check that full_page_writes is enabled. We can get torn pages if
 	 * a page is modified while we read it with pg_read_binary_file(), and we
 	 * rely on full page images to fix them.
 	 */
@@ -465,5 +465,5 @@ execute_pagemap(datapagemap_t *pagemap, const char *path)
 
 		fetch_file_range(path, offset, offset + BLCKSZ);
 	}
-	free(iter);
+	pg_free(iter);
 }
diff --git a/src/bin/pg_rewind/logging.h b/src/bin/pg_rewind/logging.h
index 0272a22039..efbc9b7bb9 100644
--- a/src/bin/pg_rewind/logging.h
+++ b/src/bin/pg_rewind/logging.h
@@ -32,4 +32,4 @@ extern void pg_fatal(const char *fmt,...) pg_attribute_printf(1, 2) pg_attribute
 
 extern void progress_report(bool force);
 
-#endif
+#endif   /* PG_REWIND_LOGGING_H */
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 8088be4fab..7e54ac55fc 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -121,7 +121,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:NnP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nP", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -370,7 +370,7 @@ sanityChecks(void)
 	if (ControlFile_target.data_checksum_version != PG_DATA_CHECKSUM_VERSION &&
 		!ControlFile_target.wal_log_hints)
 	{
-		pg_fatal("target server need to use either data checksums or \"wal_log_hints = on\"\n");
+		pg_fatal("target server needs to use either data checksums or \"wal_log_hints = on\"\n");
 	}
 
 	/*
@@ -450,7 +450,7 @@ findCommonAncestorTimeline(XLogRecPtr *recptr, TimeLineID *tli)
 			*recptr = entry->end;
 			*tli = entry->tli;
 
-			free(sourceHistory);
+			pg_free(sourceHistory);
 			return;
 		}
 	}