diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index d12d35218ee..80786c0d924 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -6458,9 +6458,7 @@ passwordFromFile(char *hostname, char *port, char *dbname,
 {
 	FILE	   *fp;
 	struct stat stat_buf;
-
-#define LINELEN NAMEDATALEN*5
-	char		buf[LINELEN];
+	PQExpBufferData buf;
 
 	if (dbname == NULL || dbname[0] == '\0')
 		return NULL;
@@ -6516,63 +6514,81 @@ passwordFromFile(char *hostname, char *port, 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;
-
-		if (fgets(buf, sizeof(buf), fp) == NULL)
+		/* Make sure there's a reasonable amount of room in the buffer */
+		if (!enlargePQExpBuffer(&buf, 128))
 			break;
 
-		len = strlen(buf);
+		/* 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);
 
-		/* Remove trailing newline */
-		if (len > 0 && buf[len - 1] == '\n')
-		{
-			buf[--len] = '\0';
-			/* Handle DOS-style line endings, too, even when not on Windows */
-			if (len > 0 && buf[len - 1] == '\r')
-				buf[--len] = '\0';
-		}
-
-		if (len == 0)
+		/* 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;
 
-		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)
+		/* ignore comments */
+		if (buf.data[0] != '#')
 		{
-			/* Out of memory. XXX: an error message would be nice. */
-			return NULL;
+			char	   *t = buf.data;
+			int			len = buf.len;
+
+			/* Remove trailing newline */
+			if (len > 0 && t[len - 1] == '\n')
+			{
+				t[--len] = '\0';
+				/* Handle DOS-style line endings, too */
+				if (len > 0 && t[len - 1] == '\r')
+					t[--len] = '\0';
+			}
+
+			if (len > 0 &&
+				(t = pwdfMatchesString(t, hostname)) != NULL &&
+				(t = pwdfMatchesString(t, port)) != NULL &&
+				(t = pwdfMatchesString(t, dbname)) != NULL &&
+				(t = pwdfMatchesString(t, username)) != NULL)
+			{
+				/* Found a match. */
+				char	   *ret,
+						   *p1,
+						   *p2;
+
+				ret = strdup(t);
+
+				fclose(fp);
+				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;
+			}
 		}
 
-		/* 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);
+	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 9340f2f1ab4..5a62ac1eb0b 100644
--- a/src/test/authentication/t/001_password.pl
+++ b/src/test/authentication/t/001_password.pl
@@ -17,7 +17,7 @@ if ($windows_os)
 }
 else
 {
-	plan tests => 8;
+	plan tests => 11;
 }
 
 
@@ -44,7 +44,9 @@ 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 $role");
 }
@@ -83,3 +85,25 @@ test_role($node, 'md5_role',   'scram-sha-256', 2);
 reset_pg_hba($node, 'md5');
 test_role($node, 'scram_role', 'md5', 0);
 test_role($node, 'md5_role',   'md5', 0);
+
+# Test .pgpass processing; but use a temp file, don't overwrite the real one!
+my $pgpassfile = "${TestLib::tmp_check}/pgpass";
+
+delete $ENV{"PGPASSWORD"};
+$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);