diff --git a/lib/rscons/builders/program.rb b/lib/rscons/builders/program.rb
index 4dd9414..4bca0fb 100644
--- a/lib/rscons/builders/program.rb
+++ b/lib/rscons/builders/program.rb
@@ -1,4 +1,19 @@
 module Rscons
   class Program < Builder
+    def default_variables
+      {
+        'CC' => 'gcc',
+        'CFLAGS' => [],
+        'CPPFLAGS' => [],
+        'OBJSUFFIX' => '.o',
+        'CSUFFIX' => '.c',
+        'CCDEPGEN' => ['-MMD', '-MF', '$DEPFILE'],
+        'CCCOM' => ['$CC', '-c', '-o', '$TARGET', '$CCDEPGEN', '$CPPFLAGS', '$CFLAGS', '$SOURCES']
+      }
+    end
+
+    def produces?(target, source)
+      target.has_suffix?(@env['OBJSUFFIX']) and source.has_suffix?(@env['CSUFFIX'])
+    end
   end
 end
diff --git a/lib/rscons/monkey/string.rb b/lib/rscons/monkey/string.rb
new file mode 100644
index 0000000..b5dbc41
--- /dev/null
+++ b/lib/rscons/monkey/string.rb
@@ -0,0 +1,10 @@
+class String
+  def has_suffix?(suffix)
+    suffix = [suffix] if suffix.is_a?(String)
+    suffix.find {|s| self =~ /#{s}$/}
+  end
+
+  def set_suffix(suffix = '')
+    sub(/\.[^.]*$/, suffix)
+  end
+end