diff --git a/.travis.yml b/.travis.yml
index 4ce58caf..947d9543 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,6 +8,6 @@ env:
   - BUILD_TYPE=Release
 
 script:
-  - cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE .
+  - cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DFMT_EXTRA_TESTS=ON .
   - make -j4
   - make test
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1554e253..a0c61dac 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,6 +8,8 @@ if (NOT CMAKE_BUILD_TYPE)
     "Choose the type of build, options are: None(CMAKE_CXX_FLAGS or CMAKE_C_FLAGS used) Debug Release RelWithDebInfo MinSizeRel.")
 endif ()
 
+option(FMT_EXTRA_TESTS "Enable extra tests." OFF)
+
 project(FORMAT)
 
 include(CheckCXXCompilerFlag)
@@ -49,7 +51,7 @@ if (CMAKE_COMPILER_IS_GNUCXX)
   set_target_properties(format PROPERTIES COMPILE_FLAGS
     "-Wall -Wextra -pedantic")
 endif ()
-if (CPP11_FLAG)
+if (CPP11_FLAG AND FMT_EXTRA_TESTS)
   set_target_properties(format PROPERTIES COMPILE_FLAGS ${CPP11_FLAG})
   # Test compilation with default flags.
   file(GLOB src RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} test/*.cc test/*.h)
diff --git a/appveyor.yml b/appveyor.yml
index cc50a30a..eed7fea9 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -5,7 +5,7 @@ configuration:
 install:
   - set PATH=C:\Program Files (x86)\MSBuild\12.0\bin\;%PATH%
 
-before_build: cmake .
+before_build: cmake -DFMT_EXTRA_TESTS=ON .
 
 build_script:
   - msbuild /m:4 FORMAT.sln