diff --git a/client/html/post_merge_side.tpl b/client/html/post_merge_side.tpl
index 53dd31f..a4e77ed 100644
--- a/client/html/post_merge_side.tpl
+++ b/client/html/post_merge_side.tpl
@@ -36,6 +36,7 @@
                     'image/jpeg': 'JPEG',
                     'image/png': 'PNG',
                     'image/webp': 'WEBP',
+                    'image/bmp': 'BMP',
                     'video/webm': 'WEBM',
                     'video/mp4': 'MPEG-4',
                     'application/x-shockwave-flash': 'SWF',
diff --git a/client/html/post_readonly_sidebar.tpl b/client/html/post_readonly_sidebar.tpl
index cfbfd10..a54e7bb 100644
--- a/client/html/post_readonly_sidebar.tpl
+++ b/client/html/post_readonly_sidebar.tpl
@@ -9,6 +9,7 @@
                     'image/jpeg': 'JPEG',
                     'image/png': 'PNG',
                     'image/webp': 'WEBP',
+                    'image/bmp': 'BMP',
                     'video/webm': 'WEBM',
                     'video/mp4': 'MPEG-4',
                     'application/x-shockwave-flash': 'SWF',
diff --git a/client/js/views/post_upload_view.js b/client/js/views/post_upload_view.js
index 7daf4fb..f1eb47c 100644
--- a/client/js/views/post_upload_view.js
+++ b/client/js/views/post_upload_view.js
@@ -15,6 +15,7 @@ function _mimeTypeToPostType(mimeType) {
             "image/jpeg": "image",
             "image/png": "image",
             "image/webp": "image",
+            "image/bmp": "image",
             "video/mp4": "video",
             "video/webm": "video",
         }[mimeType] || "unknown"
@@ -109,6 +110,7 @@ class Url extends Uploadable {
             png: "image/png",
             gif: "image/gif",
             webp: "image/webp",
+            bmp: "image/bmp",
             mp4: "video/mp4",
             webm: "video/webm",
         };
diff --git a/server/szurubooru/func/mime.py b/server/szurubooru/func/mime.py
index bd553fc..e521c25 100644
--- a/server/szurubooru/func/mime.py
+++ b/server/szurubooru/func/mime.py
@@ -21,6 +21,9 @@ def get_mime_type(content: bytes) -> str:
     if content[8:12] == b"WEBP":
         return "image/webp"
 
+    if content[0:2] == b"BM":
+        return "image/bmp"
+
     if content[0:4] == b"\x1A\x45\xDF\xA3":
         return "video/webm"
 
@@ -37,6 +40,7 @@ def get_extension(mime_type: str) -> Optional[str]:
         "image/jpeg": "jpg",
         "image/png": "png",
         "image/webp": "webp",
+        "image/bmp": "bmp",
         "video/mp4": "mp4",
         "video/webm": "webm",
         "application/octet-stream": "dat",
@@ -58,6 +62,7 @@ def is_image(mime_type: str) -> bool:
         "image/png",
         "image/gif",
         "image/webp",
+        "image/bmp",
     )
 
 
diff --git a/server/szurubooru/tests/assets/bmp.bmp b/server/szurubooru/tests/assets/bmp.bmp
new file mode 100644
index 0000000..3a18269
Binary files /dev/null and b/server/szurubooru/tests/assets/bmp.bmp differ
diff --git a/server/szurubooru/tests/func/test_mime.py b/server/szurubooru/tests/func/test_mime.py
index 0d8f645..62fd4a7 100644
--- a/server/szurubooru/tests/func/test_mime.py
+++ b/server/szurubooru/tests/func/test_mime.py
@@ -13,6 +13,7 @@ from szurubooru.func import mime
         ("jpeg.jpg", "image/jpeg"),
         ("gif.gif", "image/gif"),
         ("webp.webp", "image/webp"),
+        ("bmp.bmp", "image/bmp"),
         ("text.txt", "application/octet-stream"),
     ],
 )
@@ -34,6 +35,7 @@ def test_get_mime_type_for_empty_file():
         ("image/jpeg", "jpg"),
         ("image/gif", "gif"),
         ("image/webp", "webp"),
+        ("image/bmp", "bmp"),
         ("application/octet-stream", "dat"),
     ],
 )
@@ -75,9 +77,11 @@ def test_is_video(input_mime_type, expected_state):
         ("image/gif", True),
         ("image/png", True),
         ("image/jpeg", True),
+        ("image/bmp", True),
         ("IMAGE/GIF", True),
         ("IMAGE/PNG", True),
         ("IMAGE/JPEG", True),
+        ("IMAGE/BMP", True),
         ("image/anything_else", False),
         ("not an image", False),
     ],
diff --git a/server/szurubooru/tests/func/test_posts.py b/server/szurubooru/tests/func/test_posts.py
index 6139555..0693741 100644
--- a/server/szurubooru/tests/func/test_posts.py
+++ b/server/szurubooru/tests/func/test_posts.py
@@ -392,6 +392,13 @@ def test_update_post_source_with_too_long_string():
             model.Post.TYPE_IMAGE,
             "1_244c8840887984c4.gif",
         ),
+        (
+            False,
+            "bmp.bmp",
+            "image/bmp",
+            model.Post.TYPE_IMAGE,
+            "1_244c8840887984c4.bmp",
+        ),
         (
             False,
             "gif-animated.gif",