Apparently Ruby 1.8 doesn't have Proc.source_location

Gemfile

@@ -27,6 +27,11 @@ platforms :ruby do
   gem "redcarpet"
 end
 
+# Cross-templating language block fix for Ruby 1.8
+platforms :ruby_18 do
+  gem "ruby18_source_location"
+end
+
 platforms :jruby do
   gem "therubyrhino"
 end

middleman-core/lib/middleman-core/templates/empty/Gemfile.tt

@@ -1,3 +1,8 @@
 source 'https://rubygems.org'
 
 gem "middleman", "~><%= Middleman::VERSION %>"
+
+# Cross-templating language block fix for Ruby 1.8
+platforms :ruby_18 do
+  gem "ruby18_source_location"
+end

middleman-core/lib/middleman-core/templates/shared/Gemfile.tt

@@ -9,3 +9,8 @@ gem "middleman-livereload", "~> 3.1.0"
 
 # For faster file watcher updates:
 # gem "wdm", "~> 0.1.0") # Windows
+
+# Cross-templating language block fix for Ruby 1.8
+platforms :ruby_18 do
+  gem "ruby18_source_location"
+end

middleman-core/lib/middleman-more/core_extensions/default_helpers.rb

@@ -1,3 +1,13 @@
+# Required to hack around Padrino blocks within different template types.
+if RUBY_VERSION < "1.9.0"
+  begin
+    require 'ruby18_source_location'
+  rescue LoadError
+    $stderr.puts "Ruby 1.8 requires the 'ruby18_source_location' gem be added to your Gemfile"
+    exit(1)
+  end
+end
+
 if !defined?(::Padrino::Helpers)
   require 'vendored-middleman-deps/padrino-core-0.11.2/lib/padrino-core/support_lite'
   require 'vendored-middleman-deps/padrino-helpers-0.11.2/lib/padrino-helpers'