diff --git a/lib/asciidoctor-epub3/converter.rb b/lib/asciidoctor-epub3/converter.rb
index 8cfcf7e..a78cf27 100644
--- a/lib/asciidoctor-epub3/converter.rb
+++ b/lib/asciidoctor-epub3/converter.rb
@@ -1000,7 +1000,7 @@ def register_media_file node, target, media_type
 
       def resolve_image_attrs node
         img_attrs = []
-        img_attrs << %(alt="#{node.attr 'alt'}") if node.attr? 'alt'
+        img_attrs << %(alt="#{encode_alt_text node, (node.attr 'alt'), true}") if node.attr? 'alt'
 
         # Unlike browsers, Calibre/Kindle *do* scale image if only height is specified
         # So, in order to match browser behavior, we just always omit height
@@ -1765,6 +1765,11 @@ def class_string node
       def role_valid_class? role
         role.is_a? String
       end
+
+      def encode_alt_text node, val, to_attr = false
+        val = node.sub_specialchars val if (val.include? '<') || (val.include? '&') || (val.include? '>')
+        to_attr && (val.include? '"') ? (val.gsub '"', '&quot;') : val
+      end
     end
 
     class DocumentIdGenerator