diff --git a/.versioneer-lookup b/.versioneer-lookup
index 86ee131b..d753c1c0 100644
--- a/.versioneer-lookup
+++ b/.versioneer-lookup
@@ -15,9 +15,10 @@ HEAD
 \(detached.*
 
 # maintenance is currently the branch for preparation of maintenance release 1.2.9
-# so are any fix/... branches
+# so are any fix/... and improve/... branches
 maintenance 1.2.9 dedadbc9ac0305799e94ae279d3bca131629c4c5 pep440-dev
 fix/.* 1.2.9 dedadbc9ac0305799e94ae279d3bca131629c4c5 pep440-dev
+improve/.* 1.2.9 dedadbc9ac0305799e94ae279d3bca131629c4c5 pep440-dev
 
 # every other branch is a development branch and thus gets resolved to 1.3.0-dev for now
 .* 1.3.0 198d3450d94be1a2 pep440-dev
diff --git a/src/octoprint/server/views.py b/src/octoprint/server/views.py
index 4072e9cc..14a8c3bc 100644
--- a/src/octoprint/server/views.py
+++ b/src/octoprint/server/views.py
@@ -17,6 +17,7 @@ from octoprint.server import app, userManager, pluginManager, gettext, \
 	debug, LOCALES, VERSION, DISPLAY_VERSION, UI_API_KEY, BRANCH, preemptiveCache, \
 	NOT_MODIFIED
 from octoprint.settings import settings
+from octoprint.filemanager import get_all_extensions
 
 import re
 
@@ -249,6 +250,7 @@ def _get_render_kwargs(templates, plugin_names, plugin_vars, now):
 
 	first_run = settings().getBoolean(["server", "firstRun"])
 	locales = dict((l.language, dict(language=l.language, display=l.display_name, english=l.english_name)) for l in LOCALES)
+	extensions = map(lambda ext: ".{}".format(ext), get_all_extensions())
 
 	#~~ prepare full set of template vars for rendering
 
@@ -260,6 +262,7 @@ def _get_render_kwargs(templates, plugin_names, plugin_vars, now):
 		templates=templates,
 		pluginNames=plugin_names,
 		locales=locales,
+		supportedExtensions=extensions
 	)
 	render_kwargs.update(plugin_vars)
 
diff --git a/src/octoprint/templates/sidebar/files.jinja2 b/src/octoprint/templates/sidebar/files.jinja2
index 6efa2b14..6fada5eb 100644
--- a/src/octoprint/templates/sidebar/files.jinja2
+++ b/src/octoprint/templates/sidebar/files.jinja2
@@ -54,18 +54,18 @@
             <span class="btn btn-primary fileinput-button span6" data-bind="css: {disabled: !$root.loginState.isUser()}" style="margin-bottom: 10px">
                                 <i class="icon-upload-alt icon-white"></i>
                                 <span>{{ _('Upload') }}</span>
-                                <input id="gcode_upload" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser()">
+                                <input id="gcode_upload" accept="{{ ",".join(supportedExtensions) }}" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser()">
                             </span>
             <span class="btn btn-primary fileinput-button span6" data-bind="css: {disabled: !$root.loginState.isUser() || !$root.isSdReady()}" style="margin-bottom: 10px">
                                 <i class="icon-upload-alt icon-white"></i>
                                 <span>{{ _('Upload to SD') }}</span>
-                                <input id="gcode_upload_sd" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser() && isSdReady()">
+                                <input id="gcode_upload_sd" accept="{{ ",".join(supportedExtensions) }}" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser() && isSdReady()">
                             </span>
         {% else %}
             <span class="btn btn-primary fileinput-button span12" data-bind="css: {disabled: !$root.loginState.isUser()}" style="margin-bottom: 10px">
                                 <i class="icon-upload-alt icon-white"></i>
                                 <span>{{ _('Upload') }}</span>
-                                <input id="gcode_upload" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser()">
+                                <input id="gcode_upload" accept="{{ ",".join(supportedExtensions) }}" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser()">
                             </span>
         {% endif %}
     </div>