diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3c49ad2..d005e15 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -29,6 +29,8 @@ if(build_tests)
   enable_testing()
   include_directories($ENV{GTEST_ROOT}/include)
   link_directories($ENV{GTEST_ROOT})
+  include_directories($ENV{GFLAGS_ROOT}/include)
+  link_directories($ENV{GFLAGS_ROOT}/lib)
   add_executable(btree_test btree_test.cc btree_test_flags.cc)
   add_executable(safe_btree_test safe_btree_test.cc btree_test_flags.cc)
   add_executable(btree_bench btree_bench.cc btree_test_flags.cc)
diff --git a/README b/README
index 0e8674c..319fe9b 100644
--- a/README
+++ b/README
@@ -11,10 +11,21 @@ CMake, the Google C++ Test framework, and the Google flags package.
 
 Download and install CMake from http://www.cmake.org
 
-Download and build the GoogleTest framework from http://code.google.com/p/googletest
+Download and build the GoogleTest framework from
+http://code.google.com/p/googletest
 
 Download and install gflags from https://code.google.com/p/gflags
 
+Set GTEST_ROOT to the directory where GTEST was built.
+Set GFLAGS_ROOT to the directory prefix where GFLAGS is installed.
+
 export GTEST_ROOT=/path/for/gtest-x.y
+export GFLAGS_ROOT=/opt
 
 cmake . -Dbuild_tests=ON
+
+For example, to build on a Unix system with the clang++ compiler,
+
+export GTEST_ROOT=$(HOME)/src/googletest
+export GFLAGS_ROOT=/opt
+cmake . -G "Unix Makefiles" -Dbuild_tests=ON -DCMAKE_CXX_COMPILER=clang++
diff --git a/btree_bench.cc b/btree_bench.cc
index d5495c5..900c5e6 100644
--- a/btree_bench.cc
+++ b/btree_bench.cc
@@ -133,7 +133,7 @@ void BenchmarkRun::Reset() {
 void BenchmarkRun::Run() {
   assert(current_benchmark == NULL);
   current_benchmark = this;
-  int iters = FLAGS_benchmark_min_iters;
+  int64_t iters = FLAGS_benchmark_min_iters;
   for (;;) {
     Reset();
     Start();
@@ -152,7 +152,7 @@ void BenchmarkRun::Run() {
   }
   fprintf(stdout, "%s\t%qu\t%qu\n", 
 	  benchmark_name, 
-	  accum_micros * 1000 / iters, 
+	  accum_micros * 1000ULL / iters, 
 	  iters);
   current_benchmark = NULL;
 }