diff --git a/amadeus/static/js/mural.js b/amadeus/static/js/mural.js
index fdf9925..939fcfc 100644
--- a/amadeus/static/js/mural.js
+++ b/amadeus/static/js/mural.js
@@ -91,7 +91,12 @@ function seeComplete(btn, post) {
 function setPostFormSubmit(post = "") {
     var frm = $('#post-form');
 
-    frm.submit(function () {
+    frm.submit(function (e) {
+        var btn = frm.parent().parent().parent().find("button[form='post-form']")
+
+        btn.prop('disable', true);
+        btn.prop('disabled', true);
+
         var formData = new FormData($(this)[0]);
 
         $.ajax({
diff --git a/chat/models.py b/chat/models.py
index 8c5a05d..aaaf16e 100644
--- a/chat/models.py
+++ b/chat/models.py
@@ -11,9 +11,9 @@ from datetime import timezone
 from subjects.models import Subject
 from users.models import User
 
+valid_formats = ['image/jpeg','image/x-citrix-jpeg','image/png','image/x-citrix-png','image/x-png','image/gif']
+
 def validate_img_extension(value):
-	valid_formats = ['image/jpeg','image/x-citrix-jpeg','image/png','image/x-citrix-png','image/x-png','image/gif']
-	
 	if hasattr(value.file, 'content_type'):
 		if not value.file.content_type in valid_formats:
 			raise ValidationError(_('Select a valid file. The file must posses one of this extensions: .jpg, .png, .gif'))
diff --git a/mural/models.py b/mural/models.py
index bc0994a..b10bec0 100644
--- a/mural/models.py
+++ b/mural/models.py
@@ -10,9 +10,9 @@ from subjects.models import Subject
 from topics.models import KnowsChild, Resource
 from users.models import User
 
-def validate_img_extension(value):
-	valid_formats = ['image/jpeg','image/x-citrix-jpeg','image/png','image/x-citrix-png','image/x-png']
+valid_formats = ['image/jpeg','image/x-citrix-jpeg','image/png','image/x-citrix-png','image/x-png','image/gif']
 
+def validate_img_extension(value):
 	if hasattr(value.file, 'content_type'):
 		if not value.file.content_type in valid_formats:
 			raise ValidationError(_('File not supported.'))
diff --git a/mural/templates/mural/_form.html b/mural/templates/mural/_form.html
index 5ff980b..1b63f48 100644
--- a/mural/templates/mural/_form.html
+++ b/mural/templates/mural/_form.html
@@ -80,24 +80,35 @@
 
 					<span id="helpBlock" class="help-block">{{ form.image.help_text }}</span>
 
-					{% if form.image.errors %}
-						<div class="alert alert-danger alert-dismissible" role="alert">
-								<button type="button" class="close" data-dismiss="alert" aria-label="Close">
-									<span aria-hidden="true">&times;</span>
-								</button>
-							<ul>
-								{% for error in form.image.errors %}
-									<li>{{ error }}</li>
-								{% endfor %}
-							</ul>
-						</div>
-					{% endif %}
+				</div>
+				
+				{% if form.image.errors %}
+					<div class="alert alert-danger alert-dismissible" role="alert">
+							<button type="button" class="close" data-dismiss="alert" aria-label="Close">
+								<span aria-hidden="true">&times;</span>
+							</button>
+						<ul>
+							{% for error in form.image.errors %}
+								<li>{{ error }}</li>
+							{% endfor %}
+						</ul>
+					</div>
+				{% endif %}
+
+				<div class="alert alert-danger alert-dismissible client-file-errors" style="display:none" role="alert">
+						<button type="button" class="close" data-dismiss="alert" aria-label="Close">
+							<span aria-hidden="true">&times;</span>
+						</button>
+					<ul>
+						<li class="size" style="display:none">{% trans "The image is too large. It should have less than 5MB." %}</li>
+						<li class="format" style="display:none">{% trans 'File not supported.' %}</li>
+					</ul>
 				</div>
 			</form>
 		</div>
 		<div class="modal-footer">
 			<div class="col-md-12">
-				<button type="submit" id="button" form="post-form" class="btn btn-success btn-raised post-button pull-left">{% trans "Post" context "button"%}</button>
+				<button type="submit" id="button" form="post-form" class="btn btn-success btn-raised post-button pull-left">{% trans "Post" context "button" %}</button>
 				<button type="button" class="btn btn-raised btn-default pull-right" data-dismiss="modal">{% trans "Cancel" %}</button>
 			</div>
 		</div>
@@ -147,10 +158,33 @@
 	// file selection
 	function FileSelectHandler(e) {
 		var files = e.target.files || e.dataTransfer.files,
-			parent = $(e.target.offsetParent);
+			parent = $(e.target.offsetParent),
+			max_size = 5*1024*1024;
+
+		$(".client-file-errors").hide();
+		$(".size").hide();
+		$(".format").hide();
+		$("#button").prop('disable', false);
+		$("#button").prop('disabled', false);
 
 		// process all File objects
 		for (var i = 0, f; f = files[i]; i++) {
+			if (f.size > max_size) {
+				$("#button").prop('disable', true);
+				$("#button").prop('disabled', true);
+
+				$(".client-file-errors").show();
+				$(".size").show();
+			} 
+
+			if (!f.type.match(/^image\//)) {
+				$("#button").prop('disable', true);
+				$("#button").prop('disabled', true);
+
+				$(".client-file-errors").show();
+				$(".format").show();
+			}
+
 			parent.find('.filedrag').html(f.name);
 		}
 	}
--
libgit2 0.21.2