diff --git a/app/models/principal.rb b/app/models/principal.rb
index 82c17b472f..495d55669e 100644
--- a/app/models/principal.rb
+++ b/app/models/principal.rb
@@ -72,16 +72,16 @@ class Principal < ActiveRecord::Base
       where({})
     else
       pattern = "%#{sanitize_sql_like q}%"
-      sql = +"LOWER(#{table_name}.login) LIKE LOWER(:p)"
-      sql << " OR #{table_name}.id IN (SELECT user_id FROM #{EmailAddress.table_name} WHERE LOWER(address) LIKE LOWER(:p))"
-      params = {:p => pattern}
+      sql = +"LOWER(#{table_name}.login) LIKE LOWER(:p) ESCAPE :s"
+      sql << " OR #{table_name}.id IN (SELECT user_id FROM #{EmailAddress.table_name} WHERE LOWER(address) LIKE LOWER(:p) ESCAPE :s)"
+      params = {:p => pattern, :s => '\\'}
 
       tokens = q.split(/\s+/).reject(&:blank?).map {|token| "%#{sanitize_sql_like token}%"}
       if tokens.present?
         sql << ' OR ('
         sql << tokens.map.with_index do |token, index|
           params[:"token_#{index}"] = token
-          "(LOWER(#{table_name}.firstname) LIKE LOWER(:token_#{index}) OR LOWER(#{table_name}.lastname) LIKE LOWER(:token_#{index}))"
+          "(LOWER(#{table_name}.firstname) LIKE LOWER(:token_#{index}) ESCAPE :s OR LOWER(#{table_name}.lastname) LIKE LOWER(:token_#{index}) ESCAPE :s)"
         end.join(' AND ')
         sql << ')'
       end
diff --git a/app/models/project.rb b/app/models/project.rb
index c99badb724..429189fc30 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -108,7 +108,7 @@ class Project < ActiveRecord::Base
   scope :like, (lambda do |arg|
     if arg.present?
       pattern = "%#{sanitize_sql_like arg.to_s.strip}%"
-      where("LOWER(identifier) LIKE LOWER(:p) OR LOWER(name) LIKE LOWER(:p)", :p => pattern)
+      where("LOWER(identifier) LIKE LOWER(:p) ESCAPE :s OR LOWER(name) LIKE LOWER(:p) ESCAPE :s", :p => pattern, :s => '\\')
     end
   end)
   scope :sorted, lambda {order(:lft)}
diff --git a/lib/redmine/database.rb b/lib/redmine/database.rb
index 2d84ff35e2..ecc2001436 100644
--- a/lib/redmine/database.rb
+++ b/lib/redmine/database.rb
@@ -71,8 +71,10 @@ module Redmine
           else
             "#{left} #{neg}ILIKE #{right}"
           end
-        else
+        elsif mysql?
           "#{left} #{neg}LIKE #{right}"
+        else
+          "#{left} #{neg}LIKE #{right} ESCAPE '\\'"
         end
       end