diff --git a/README.md b/README.md
index 1f7def7..585a42e 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ Requirements
 ------------
 
 * CUPS: tested with version 1.6.
-* A C++11 compiler. A recent version of GCC or Clang will work.
+* A C++11 compiler: GCC 4.6 or later, or a recent version of Clang.
 
 Copyright
 ---------
diff --git a/src/brdecode.cc b/src/brdecode.cc
index 8be0549..17f3685 100644
--- a/src/brdecode.cc
+++ b/src/brdecode.cc
@@ -16,6 +16,7 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <stdint.h>
+#include <stdio.h>
 #include <unistd.h>
 #include <algorithm>
 #include <exception>
@@ -127,9 +128,9 @@ void read_line() {
 }
 
 void read_block() {
-  uint8_t count = get();
+  unsigned count = get();
   count = count * 256 + get();
-  for (int i = 0; i < count; ++i) {
+  for (unsigned i = 0; i < count; ++i) {
     read_line();
   }
 }
diff --git a/src/job.cc b/src/job.cc
index 5336463..535d60d 100644
--- a/src/job.cc
+++ b/src/job.cc
@@ -27,6 +27,9 @@ namespace {
 
 class block {
  public:
+  block(): line_bytes_(0) {
+  }
+
   void add_line(vector<uint8_t> &&line) {
     assert(!line.empty());
     line_bytes_ += line.size();
@@ -52,11 +55,11 @@ class block {
   }
 
  private:
-  const unsigned max_block_size_ = 16350;
-  const unsigned max_lines_per_block_ = 128;
+  static const unsigned max_block_size_ = 16350;
+  static const unsigned max_lines_per_block_ = 128;
 
   vector<vector<uint8_t>> lines_;
-  int line_bytes_ = 0;
+  int line_bytes_;
 };
 
 }  // namespace