diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 86e196064e..b4d2407171 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -6933,10 +6933,7 @@ passwordFromFile(const char *hostname, const char *port, const char *dbname,
 {
 	FILE	   *fp;
 	struct stat stat_buf;
-	int			line_number = 0;
-
-#define LINELEN NAMEDATALEN*5
-	char		buf[LINELEN];
+	PQExpBufferData buf;
 
 	if (dbname == NULL || dbname[0] == '\0')
 		return NULL;
@@ -6992,89 +6989,77 @@ passwordFromFile(const char *hostname, const char *port, const char *dbname,
 	if (fp == NULL)
 		return NULL;
 
+	/* Use an expansible buffer to accommodate any reasonable line length */
+	initPQExpBuffer(&buf);
+
 	while (!feof(fp) && !ferror(fp))
 	{
-		char	   *t = buf,
-				   *ret,
-				   *p1,
-				   *p2;
-		int			len;
-		int			buflen;
-
-		if (fgets(buf, sizeof(buf), fp) == NULL)
+		/* Make sure there's a reasonable amount of room in the buffer */
+		if (!enlargePQExpBuffer(&buf, 128))
 			break;
 
-		line_number++;
-		buflen = strlen(buf);
-		if (buflen >= sizeof(buf) - 1 && buf[buflen - 1] != '\n')
+		/* Read some data, appending it to what we already have */
+		if (fgets(buf.data + buf.len, buf.maxlen - buf.len, fp) == NULL)
+			break;
+		buf.len += strlen(buf.data + buf.len);
+
+		/* If we don't yet have a whole line, loop around to read more */
+		if (!(buf.len > 0 && buf.data[buf.len - 1] == '\n') && !feof(fp))
+			continue;
+
+		/* ignore comments */
+		if (buf.data[0] != '#')
 		{
-			char		rest[LINELEN];
-			int			restlen;
+			char	   *t = buf.data;
+			int			len;
 
-			/*
-			 * Warn if this password setting line is too long, because it's
-			 * unexpectedly truncated.
-			 */
-			if (buf[0] != '#')
-				fprintf(stderr,
-						libpq_gettext("WARNING: line %d too long in password file \"%s\"\n"),
-						line_number, pgpassfile);
+			/* strip trailing newline and carriage return */
+			len = pg_strip_crlf(t);
 
-			/* eat rest of the line */
-			while (!feof(fp) && !ferror(fp))
+			if (len > 0 &&
+				(t = pwdfMatchesString(t, hostname)) != NULL &&
+				(t = pwdfMatchesString(t, port)) != NULL &&
+				(t = pwdfMatchesString(t, dbname)) != NULL &&
+				(t = pwdfMatchesString(t, username)) != NULL)
 			{
-				if (fgets(rest, sizeof(rest), fp) == NULL)
-					break;
-				restlen = strlen(rest);
-				if (restlen < sizeof(rest) - 1 || rest[restlen - 1] == '\n')
-					break;
+				/* Found a match. */
+				char	   *ret,
+						   *p1,
+						   *p2;
+
+				ret = strdup(t);
+
+				fclose(fp);
+				explicit_bzero(buf.data, buf.maxlen);
+				termPQExpBuffer(&buf);
+
+				if (!ret)
+				{
+					/* Out of memory. XXX: an error message would be nice. */
+					return NULL;
+				}
+
+				/* De-escape password. */
+				for (p1 = p2 = ret; *p1 != ':' && *p1 != '\0'; ++p1, ++p2)
+				{
+					if (*p1 == '\\' && p1[1] != '\0')
+						++p1;
+					*p2 = *p1;
+				}
+				*p2 = '\0';
+
+				return ret;
 			}
 		}
 
-		/* ignore comments */
-		if (buf[0] == '#')
-			continue;
-
-		/* strip trailing newline and carriage return */
-		len = pg_strip_crlf(buf);
-
-		if (len == 0)
-			continue;
-
-		if ((t = pwdfMatchesString(t, hostname)) == NULL ||
-			(t = pwdfMatchesString(t, port)) == NULL ||
-			(t = pwdfMatchesString(t, dbname)) == NULL ||
-			(t = pwdfMatchesString(t, username)) == NULL)
-			continue;
-
-		/* Found a match. */
-		ret = strdup(t);
-		fclose(fp);
-
-		if (!ret)
-		{
-			/* Out of memory. XXX: an error message would be nice. */
-			explicit_bzero(buf, sizeof(buf));
-			return NULL;
-		}
-
-		/* De-escape password. */
-		for (p1 = p2 = ret; *p1 != ':' && *p1 != '\0'; ++p1, ++p2)
-		{
-			if (*p1 == '\\' && p1[1] != '\0')
-				++p1;
-			*p2 = *p1;
-		}
-		*p2 = '\0';
-
-		return ret;
+		/* No match, reset buffer to prepare for next line. */
+		buf.len = 0;
 	}
 
 	fclose(fp);
-	explicit_bzero(buf, sizeof(buf));
+	explicit_bzero(buf.data, buf.maxlen);
+	termPQExpBuffer(&buf);
 	return NULL;
-
-#undef LINELEN
 }
 
 
diff --git a/src/test/authentication/t/001_password.pl b/src/test/authentication/t/001_password.pl
index 82536eb60f..909003560b 100644
--- a/src/test/authentication/t/001_password.pl
+++ b/src/test/authentication/t/001_password.pl
@@ -17,7 +17,7 @@ if (!$use_unix_sockets)
 }
 else
 {
-	plan tests => 10;
+	plan tests => 13;
 }
 
 
@@ -45,7 +45,9 @@ sub test_role
 
 	$status_string = 'success' if ($expected_res eq 0);
 
-	my $res = $node->psql('postgres', undef, extra_params => [ '-U', $role ]);
+	local $Test::Builder::Level = $Test::Builder::Level + 1;
+
+	my $res = $node->psql('postgres', undef, extra_params => [ '-U', $role, '-w' ]);
 	is($res, $expected_res,
 		"authentication $status_string for method $method, role $role");
 	return;
@@ -96,3 +98,26 @@ test_role($node, 'scram_role', 'scram-sha-256', 2);
 reset_pg_hba($node, 'scram-sha-256');
 $ENV{"PGCHANNELBINDING"} = 'require';
 test_role($node, 'scram_role', 'scram-sha-256', 2);
+
+# Test .pgpass processing; but use a temp file, don't overwrite the real one!
+my $pgpassfile = "${TestLib::tmp_check}/pgpass";
+
+delete $ENV{"PGPASSWORD"};
+delete $ENV{"PGCHANNELBINDING"};
+$ENV{"PGPASSFILE"} = $pgpassfile;
+
+append_to_file($pgpassfile, qq!
+# This very long comment is just here to exercise handling of long lines in the file. This very long comment is just here to exercise handling of long lines in the file. This very long comment is just here to exercise handling of long lines in the file. This very long comment is just here to exercise handling of long lines in the file. This very long comment is just here to exercise handling of long lines in the file.
+*:*:postgres:scram_role:pass:this is not part of the password.
+!);
+chmod 0600, $pgpassfile or die;
+
+reset_pg_hba($node, 'password');
+test_role($node, 'scram_role', 'password from pgpass', 0);
+test_role($node, 'md5_role',   'password from pgpass', 2);
+
+append_to_file($pgpassfile, qq!
+*:*:*:md5_role:p\\ass
+!);
+
+test_role($node, 'md5_role',   'password from pgpass', 0);