diff --git a/lib/rscons.rb b/lib/rscons.rb
index 5f6cf82..f0b3134 100644
--- a/lib/rscons.rb
+++ b/lib/rscons.rb
@@ -5,8 +5,9 @@ require_relative "rscons/builder"
 require_relative "rscons/builder_builder"
 require_relative "rscons/builder_set"
 require_relative "rscons/cache"
-require_relative "rscons/configure_op"
 require_relative "rscons/command"
+require_relative "rscons/configure_op"
+require_relative "rscons/default_construction_variables"
 require_relative "rscons/environment"
 require_relative "rscons/script"
 require_relative "rscons/util"
diff --git a/lib/rscons/application.rb b/lib/rscons/application.rb
index 7bef69c..216f5e6 100644
--- a/lib/rscons/application.rb
+++ b/lib/rscons/application.rb
@@ -19,14 +19,9 @@ module Rscons
     #   Access any variables set on the rscons command-line.
     attr_reader :vars
 
-    # @return [VarSet]
-    #   The default construction variables provided by builders.
-    attr_reader :default_varset
-
     # Create Application instance.
     def initialize
       @n_threads = determine_n_threads
-      @default_varset = VarSet.new
       @vars = VarSet.new
     end
 
diff --git a/lib/rscons/basic_environment.rb b/lib/rscons/basic_environment.rb
index 2791673..f3642f4 100644
--- a/lib/rscons/basic_environment.rb
+++ b/lib/rscons/basic_environment.rb
@@ -9,7 +9,7 @@ module Rscons
     # @param options [Hash]
     #   Construction options.
     def initialize(options = {})
-      @varset = VarSet.new(Rscons.application.default_varset)
+      @varset = VarSet.new(Rscons::DEFAULT_CONSTRUCTION_VARIABLES)
       load_configuration_data!(options)
     end
 
diff --git a/lib/rscons/builders/cfile.rb b/lib/rscons/builders/cfile.rb
index 616bd30..0f510ba 100644
--- a/lib/rscons/builders/cfile.rb
+++ b/lib/rscons/builders/cfile.rb
@@ -8,17 +8,6 @@ module Rscons
     #   env.CFile("lex.yy.cc", "parser.ll")
     class CFile < Builder
 
-      Rscons.application.default_varset.append(
-        "YACC" => "bison",
-        "YACC_FLAGS" => ["-d"],
-        "YACC_CMD" => ["${YACC}", "${YACC_FLAGS}", "-o", "${_TARGET}", "${_SOURCES}"],
-        "YACCSUFFIX" => [".y", ".yy"],
-        "LEX" => "flex",
-        "LEX_FLAGS" => [],
-        "LEX_CMD" => ["${LEX}", "${LEX_FLAGS}", "-o", "${_TARGET}", "${_SOURCES}"],
-        "LEXSUFFIX" => [".l", ".ll"],
-      )
-
       # Run the builder to produce a build target.
       def run(options)
         if @command
diff --git a/lib/rscons/builders/disassemble.rb b/lib/rscons/builders/disassemble.rb
index 435708a..177626c 100644
--- a/lib/rscons/builders/disassemble.rb
+++ b/lib/rscons/builders/disassemble.rb
@@ -3,12 +3,6 @@ module Rscons
     # The Disassemble builder produces a disassembly listing of a source file.
     class Disassemble < Builder
 
-      Rscons.application.default_varset.append(
-        "OBJDUMP" => "objdump",
-        "DISASM_CMD" => ["${OBJDUMP}", "${DISASM_FLAGS}", "${_SOURCES}"],
-        "DISASM_FLAGS" => ["--disassemble", "--source"],
-      )
-
       # Run the builder to produce a build target.
       def run(options)
         if @command
diff --git a/lib/rscons/builders/library.rb b/lib/rscons/builders/library.rb
index 01ce15a..4c3e350 100644
--- a/lib/rscons/builders/library.rb
+++ b/lib/rscons/builders/library.rb
@@ -3,13 +3,6 @@ module Rscons
     # A default Rscons builder that produces a static library archive.
     class Library < Builder
 
-      Rscons.application.default_varset.append(
-        'AR' => 'ar',
-        'LIBSUFFIX' => '.a',
-        'ARFLAGS' => ['rcs'],
-        'ARCMD' => ['${AR}', '${ARFLAGS}', '${_TARGET}', '${_SOURCES}']
-      )
-
       # Create an instance of the Builder to build a target.
       def initialize(options)
         super(options)
diff --git a/lib/rscons/builders/object.rb b/lib/rscons/builders/object.rb
index 70a79ae..971b343 100644
--- a/lib/rscons/builders/object.rb
+++ b/lib/rscons/builders/object.rb
@@ -12,47 +12,6 @@ module Rscons
         "DC" => "DSUFFIX",
       }
 
-      Rscons.application.default_varset.append(
-        'OBJSUFFIX' => ['.o'],
-        'DEPFILESUFFIX' => '.mf',
-
-        'CPPDEFPREFIX' => '-D',
-        'INCPREFIX' => '-I',
-
-        'AS' => '${CC}',
-        'ASFLAGS' => [],
-        'ASSUFFIX' => ['.S'],
-        'ASPPPATH' => '${CPPPATH}',
-        'ASPPFLAGS' => '${CPPFLAGS}',
-        'ASDEPGEN' => ['-MMD', '-MF', '${_DEPFILE}'],
-        'ASCMD' => ['${AS}', '-c', '-o', '${_TARGET}', '${ASDEPGEN}', '${INCPREFIX}${ASPPPATH}', '${ASPPFLAGS}', '${ASFLAGS}', '${_SOURCES}'],
-
-        'CPPFLAGS' => ['${CPPDEFPREFIX}${CPPDEFINES}'],
-        'CPPDEFINES' => [],
-        'CPPPATH' => [],
-
-        'CCFLAGS' => [],
-
-        'CC' => 'gcc',
-        'CFLAGS' => [],
-        'CSUFFIX' => ['.c'],
-        'CCDEPGEN' => ['-MMD', '-MF', '${_DEPFILE}'],
-        'CCCMD' => ['${CC}', '-c', '-o', '${_TARGET}', '${CCDEPGEN}', '${INCPREFIX}${CPPPATH}', '${CPPFLAGS}', '${CFLAGS}', '${CCFLAGS}', '${_SOURCES}'],
-
-        'CXX' => 'g++',
-        'CXXFLAGS' => [],
-        'CXXSUFFIX' => ['.cc', '.cpp', '.cxx', '.C'],
-        'CXXDEPGEN' => ['-MMD', '-MF', '${_DEPFILE}'],
-        'CXXCMD' =>['${CXX}', '-c', '-o', '${_TARGET}', '${CXXDEPGEN}', '${INCPREFIX}${CPPPATH}', '${CPPFLAGS}', '${CXXFLAGS}', '${CCFLAGS}', '${_SOURCES}'],
-
-        'DC' => 'gdc',
-        'DFLAGS' => [],
-        'DSUFFIX' => ['.d'],
-        'DDEPGEN' => ['-MMD', '-MF', '${_DEPFILE}'],
-        'D_IMPORT_PATH' => [],
-        'DCCMD' => ['${DC}', '-c', '-o', '${_TARGET}', '${DDEPGEN}', '${INCPREFIX}${D_IMPORT_PATH}', '${DFLAGS}', '${_SOURCES}'],
-      )
-
       class << self
         # Return whether this builder object is capable of producing a given target
         # file name from a given source file name.
diff --git a/lib/rscons/builders/preprocess.rb b/lib/rscons/builders/preprocess.rb
index 0ef3c34..4fa8b5c 100644
--- a/lib/rscons/builders/preprocess.rb
+++ b/lib/rscons/builders/preprocess.rb
@@ -5,12 +5,6 @@ module Rscons
     # The Preprocess builder invokes the C preprocessor
     class Preprocess < Builder
 
-      Rscons.application.default_varset.append(
-        "CPP_CMD" => %w[
-          ${_PREPROCESS_CC} -E ${_PREPROCESS_DEPGEN}
-          -o ${_TARGET} ${INCPREFIX}${CPPPATH} ${CPPFLAGS} ${_SOURCES}],
-      )
-
       # Run the builder to produce a build target.
       def run(options)
         if @command
diff --git a/lib/rscons/builders/program.rb b/lib/rscons/builders/program.rb
index 2cefb4d..f977182 100644
--- a/lib/rscons/builders/program.rb
+++ b/lib/rscons/builders/program.rb
@@ -4,19 +4,6 @@ module Rscons
     # executable program.
     class Program < Builder
 
-      Rscons.application.default_varset.append(
-        'OBJSUFFIX' => '.o',
-        'PROGSUFFIX' => (Object.const_get("RUBY_PLATFORM") =~ /mingw|cygwin/ ? ".exe" : ""),
-        'LD' => nil,
-        'LIBSUFFIX' => '.a',
-        'LDFLAGS' => [],
-        'LIBPATH' => [],
-        'LIBDIRPREFIX' => '-L',
-        'LIBLINKPREFIX' => '-l',
-        'LIBS' => [],
-        'LDCMD' => ['${LD}', '-o', '${_TARGET}', '${LDFLAGS}', '${_SOURCES}', '${LIBDIRPREFIX}${LIBPATH}', '${LIBLINKPREFIX}${LIBS}']
-      )
-
       # Create an instance of the Builder to build a target.
       #
       # @param options [Hash]
diff --git a/lib/rscons/builders/shared_library.rb b/lib/rscons/builders/shared_library.rb
index 9131f66..a953568 100644
--- a/lib/rscons/builders/shared_library.rb
+++ b/lib/rscons/builders/shared_library.rb
@@ -4,16 +4,6 @@ module Rscons
     # shared library.
     class SharedLibrary < Builder
 
-      Rscons.application.default_varset.append(
-        'SHLIBPREFIX' => (RUBY_PLATFORM =~ /mingw/ ? '' : 'lib'),
-        'SHLIBSUFFIX' => (RUBY_PLATFORM =~ /mingw/ ? '.dll' : '.so'),
-        'SHLDFLAGS' => ['${LDFLAGS}', '-shared'],
-        'SHLD' => nil,
-        'SHLIBDIRPREFIX' => '-L',
-        'SHLIBLINKPREFIX' => '-l',
-        'SHLDCMD' => ['${SHLD}', '-o', '${_TARGET}', '${SHLDFLAGS}', '${_SOURCES}', '${SHLIBDIRPREFIX}${LIBPATH}', '${SHLIBLINKPREFIX}${LIBS}']
-      )
-
       class << self
         # Return a set of build features that this builder provides.
         #
diff --git a/lib/rscons/builders/shared_object.rb b/lib/rscons/builders/shared_object.rb
index ae50da6..2129541 100644
--- a/lib/rscons/builders/shared_object.rb
+++ b/lib/rscons/builders/shared_object.rb
@@ -13,23 +13,6 @@ module Rscons
         "SHDC" => "DSUFFIX",
       }
 
-      pic_flags = (RUBY_PLATFORM =~ /mingw/ ? [] : ['-fPIC'])
-      Rscons.application.default_varset.append(
-        'SHCCFLAGS' => ['${CCFLAGS}'] + pic_flags,
-
-        'SHCC' => '${CC}',
-        'SHCFLAGS' => ['${CFLAGS}'],
-        'SHCCCMD' => ['${SHCC}', '-c', '-o', '${_TARGET}', '${CCDEPGEN}', '${INCPREFIX}${CPPPATH}', '${CPPFLAGS}', '${SHCFLAGS}', '${SHCCFLAGS}', '${_SOURCES}'],
-
-        'SHCXX' => '${CXX}',
-        'SHCXXFLAGS' => ['${CXXFLAGS}'],
-        'SHCXXCMD' => ['${SHCXX}', '-c', '-o', '${_TARGET}', '${CXXDEPGEN}', '${INCPREFIX}${CPPPATH}', '${CPPFLAGS}', '${SHCXXFLAGS}', '${SHCCFLAGS}', '${_SOURCES}'],
-
-        'SHDC' => 'gdc',
-        'SHDFLAGS' => ['${DFLAGS}'] + pic_flags,
-        'SHDCCMD' => ['${SHDC}', '-c', '-o', '${_TARGET}', '${INCPREFIX}${D_IMPORT_PATH}', '${SHDFLAGS}', '${_SOURCES}'],
-      )
-
       class << self
         # Return a set of build features that this builder provides.
         #
diff --git a/lib/rscons/default_construction_variables.rb b/lib/rscons/default_construction_variables.rb
new file mode 100644
index 0000000..5f45fbf
--- /dev/null
+++ b/lib/rscons/default_construction_variables.rb
@@ -0,0 +1,82 @@
+module Rscons
+
+  on_windows = RUBY_PLATFORM =~ /mingw|cygwin/
+  pic_flags = on_windows ? [] : %w[-fPIC]
+
+  # Default Rscons construction variables.
+  DEFAULT_CONSTRUCTION_VARIABLES = {
+    "AR" => "ar",
+    "ARCMD" => %w[${AR} ${ARFLAGS} ${_TARGET} ${_SOURCES}],
+    "ARFLAGS" => %w[rcs],
+    "AS" => "${CC}",
+    "ASCMD" => %w[${AS} -c -o ${_TARGET} ${ASDEPGEN} ${INCPREFIX}${ASPPPATH} ${ASPPFLAGS} ${ASFLAGS} ${_SOURCES}],
+    "ASDEPGEN" => %w[-MMD -MF ${_DEPFILE}],
+    "ASFLAGS" => [],
+    "ASPPFLAGS" => "${CPPFLAGS}",
+    "ASPPPATH" => "${CPPPATH}",
+    "ASSUFFIX" => %w[.S],
+    "CC" => "gcc",
+    "CCCMD" => %w[${CC} -c -o ${_TARGET} ${CCDEPGEN} ${INCPREFIX}${CPPPATH} ${CPPFLAGS} ${CFLAGS} ${CCFLAGS} ${_SOURCES}],
+    "CCDEPGEN" => %w[-MMD -MF ${_DEPFILE}],
+    "CCFLAGS" => [],
+    "CFLAGS" => [],
+    "CPPDEFINES" => [],
+    "CPPDEFPREFIX" => "-D",
+    "CPPFLAGS" => %w[${CPPDEFPREFIX}${CPPDEFINES}],
+    "CPPPATH" => [],
+    "CPP_CMD" => %w[${_PREPROCESS_CC} -E ${_PREPROCESS_DEPGEN} -o ${_TARGET} ${INCPREFIX}${CPPPATH} ${CPPFLAGS} ${_SOURCES}],
+    "CSUFFIX" => %w[.c],
+    "CXX" => "g++",
+    "CXXCMD" => %w[${CXX} -c -o ${_TARGET} ${CXXDEPGEN} ${INCPREFIX}${CPPPATH} ${CPPFLAGS} ${CXXFLAGS} ${CCFLAGS} ${_SOURCES}],
+    "CXXDEPGEN" => %w[-MMD -MF ${_DEPFILE}],
+    "CXXFLAGS" => [],
+    "CXXSUFFIX" => %w[.cc .cpp .cxx .C],
+    "DC" => "gdc",
+    "DCCMD" => %w[${DC} -c -o ${_TARGET} ${DDEPGEN} ${INCPREFIX}${D_IMPORT_PATH} ${DFLAGS} ${_SOURCES}],
+    "DDEPGEN" => %w[-MMD -MF ${_DEPFILE}],
+    "DEPFILESUFFIX" => ".mf",
+    "DFLAGS" => [],
+    "DISASM_CMD" => %w[${OBJDUMP} ${DISASM_FLAGS} ${_SOURCES}],
+    "DISASM_FLAGS" => %w[--disassemble --source],
+    "DSUFFIX" => %w[.d],
+    "D_IMPORT_PATH" => [],
+    "INCPREFIX" => "-I",
+    "LD" => nil,
+    "LDCMD" => %w[${LD} -o ${_TARGET} ${LDFLAGS} ${_SOURCES} ${LIBDIRPREFIX}${LIBPATH} ${LIBLINKPREFIX}${LIBS}],
+    "LDFLAGS" => [],
+    "LEX" => "flex",
+    "LEXSUFFIX" => %w[.l .ll],
+    "LEX_CMD" => %w[${LEX} ${LEX_FLAGS} -o ${_TARGET} ${_SOURCES}],
+    "LEX_FLAGS" => [],
+    "LIBDIRPREFIX" => "-L",
+    "LIBLINKPREFIX" => "-l",
+    "LIBPATH" => [],
+    "LIBS" => [],
+    "LIBSUFFIX" => ".a",
+    "OBJDUMP" => "objdump",
+    "OBJSUFFIX" => %w[.o],
+    "PROGSUFFIX" => on_windows ? ".exe" : "",
+    "SHCC" => "${CC}",
+    "SHCCCMD" => %w[${SHCC} -c -o ${_TARGET} ${CCDEPGEN} ${INCPREFIX}${CPPPATH} ${CPPFLAGS} ${SHCFLAGS} ${SHCCFLAGS} ${_SOURCES}],
+    "SHCCFLAGS" => %w[${CCFLAGS}] + pic_flags,
+    "SHCFLAGS" => %w[${CFLAGS}],
+    "SHCXX" => "${CXX}",
+    "SHCXXCMD" => %w[${SHCXX} -c -o ${_TARGET} ${CXXDEPGEN} ${INCPREFIX}${CPPPATH} ${CPPFLAGS} ${SHCXXFLAGS} ${SHCCFLAGS} ${_SOURCES}],
+    "SHCXXFLAGS" => %w[${CXXFLAGS}],
+    "SHDC" => "gdc",
+    "SHDCCMD" => %w[${SHDC} -c -o ${_TARGET} ${INCPREFIX}${D_IMPORT_PATH} ${SHDFLAGS} ${_SOURCES}],
+    "SHDFLAGS" => %w[${DFLAGS}] + pic_flags,
+    "SHLD" => nil,
+    "SHLDCMD" => %w[${SHLD} -o ${_TARGET} ${SHLDFLAGS} ${_SOURCES} ${SHLIBDIRPREFIX}${LIBPATH} ${SHLIBLINKPREFIX}${LIBS}],
+    "SHLDFLAGS" => %w[${LDFLAGS} -shared],
+    "SHLIBDIRPREFIX" => "-L",
+    "SHLIBLINKPREFIX" => "-l",
+    "SHLIBPREFIX" => on_windows ? "" : "lib",
+    "SHLIBSUFFIX" => on_windows ? ".dll" : ".so",
+    "YACC" => "bison",
+    "YACCSUFFIX" => %w[.y .yy],
+    "YACC_CMD" => %w[${YACC} ${YACC_FLAGS} -o ${_TARGET} ${_SOURCES}],
+    "YACC_FLAGS" => %w[-d],
+  }
+
+end