diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6b2b2bbb..9b18856e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this
 project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.19.2] - 2021-11-11
+
+### Fixed
+
+- In `set_key`, add missing newline character before new entry if necessary. (#361 by
+  [@bbc2])
+
 ## [0.19.1] - 2021-08-09
 
 ### Added
@@ -292,7 +299,8 @@ project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 [@yannham]: https://github.com/yannham
 [@zueve]: https://github.com/zueve
 
-[Unreleased]: https://github.com/theskumar/python-dotenv/compare/v0.19.1...HEAD
+[Unreleased]: https://github.com/theskumar/python-dotenv/compare/v0.19.2...HEAD
+[0.19.2]: https://github.com/theskumar/python-dotenv/compare/v0.19.1...v0.19.2
 [0.19.1]: https://github.com/theskumar/python-dotenv/compare/v0.19.0...v0.19.1
 [0.19.0]: https://github.com/theskumar/python-dotenv/compare/v0.18.0...v0.19.0
 [0.18.0]: https://github.com/theskumar/python-dotenv/compare/v0.17.1...v0.18.0
diff --git a/setup.cfg b/setup.cfg
index b63622d6..d87b0a6b 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 0.19.1
+current_version = 0.19.2
 commit = True
 tag = True
 
diff --git a/src/dotenv/main.py b/src/dotenv/main.py
index b8d0a4e0..d867f023 100644
--- a/src/dotenv/main.py
+++ b/src/dotenv/main.py
@@ -167,13 +167,17 @@ def set_key(
 
     with rewrite(dotenv_path) as (source, dest):
         replaced = False
+        missing_newline = False
         for mapping in with_warn_for_invalid_lines(parse_stream(source)):
             if mapping.key == key_to_set:
                 dest.write(line_out)
                 replaced = True
             else:
                 dest.write(mapping.original.string)
+                missing_newline = not mapping.original.string.endswith("\n")
         if not replaced:
+            if missing_newline:
+                dest.write("\n")
             dest.write(line_out)
 
     return True, key_to_set, value_to_set
diff --git a/src/dotenv/version.py b/src/dotenv/version.py
index 4c1ca3c8..aa070c2c 100644
--- a/src/dotenv/version.py
+++ b/src/dotenv/version.py
@@ -1 +1 @@
-__version__ = "0.19.1"
+__version__ = "0.19.2"
diff --git a/tests/test_main.py b/tests/test_main.py
index 13e2791c..541ac5ee 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -37,6 +37,7 @@ def test_set_key_no_file(tmp_path):
         ("a=b\nc=d", "a", "e", (True, "a", "e"), "a='e'\nc=d"),
         ("a=b\nc=d\ne=f", "c", "g", (True, "c", "g"), "a=b\nc='g'\ne=f"),
         ("a=b\n", "c", "d", (True, "c", "d"), "a=b\nc='d'\n"),
+        ("a=b", "c", "d", (True, "c", "d"), "a=b\nc='d'\n"),
     ],
 )
 def test_set_key(dotenv_file, before, key, value, expected, after):