diff --git a/app/models/optimized_image.rb b/app/models/optimized_image.rb
index 6fdc3869e..b55622995 100644
--- a/app/models/optimized_image.rb
+++ b/app/models/optimized_image.rb
@@ -153,7 +153,7 @@ class OptimizedImage < ActiveRecord::Base
 
     return false if $?.exitstatus != 0
 
-    ImageOptim.new.optimize_image(to) rescue nil
+    ImageOptim.new.optimize_image!(to) rescue nil
     true
   end
 
diff --git a/lib/letter_avatar.rb b/lib/letter_avatar.rb
index ecb031727..48d333f4e 100644
--- a/lib/letter_avatar.rb
+++ b/lib/letter_avatar.rb
@@ -78,7 +78,7 @@ class LetterAvatar
 
       `convert #{instructions.join(" ")}`
 
-      ImageOptim.new.optimize_image(filename) rescue nil
+      ImageOptim.new.optimize_image!(filename) rescue nil
 
       filename
     end