diff --git a/vm/layouts.hpp b/vm/layouts.hpp
index f8672e4522..3fe89cb558 100755
--- a/vm/layouts.hpp
+++ b/vm/layouts.hpp
@@ -90,7 +90,7 @@ inline static cell tag_for(cell type)
 	return type < HEADER_TYPE ? type : OBJECT_TYPE;
 }
 
-class object;
+struct object;
 
 struct header {
 	cell value;
diff --git a/vm/master.hpp b/vm/master.hpp
index 6164c9ea30..83f0920f5b 100755
--- a/vm/master.hpp
+++ b/vm/master.hpp
@@ -19,8 +19,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
-#include <unistd.h>
-#include <sys/param.h>
 
 /* C++ headers */
 #if __GNUC__ == 4
diff --git a/vm/os-unix.hpp b/vm/os-unix.hpp
index 07ec385763..8aff18364e 100755
--- a/vm/os-unix.hpp
+++ b/vm/os-unix.hpp
@@ -1,3 +1,5 @@
+#include <unistd.h>
+#include <sys/param.h>
 #include <dirent.h>
 #include <sys/mman.h>
 #include <sys/types.h>
@@ -24,13 +26,13 @@ typedef char symbol_char;
 #define FSEEK fseeko
 
 #define FIXNUM_FORMAT "%ld"
-#define cell_FORMAT "%lu"
-#define cell_HEX_FORMAT "%lx"
+#define CELL_FORMAT "%lu"
+#define CELL_HEX_FORMAT "%lx"
 
 #ifdef FACTOR_64
-	#define cell_HEX_PAD_FORMAT "%016lx"
+	#define CELL_HEX_PAD_FORMAT "%016lx"
 #else
-	#define cell_HEX_PAD_FORMAT "%08lx"
+	#define CELL_HEX_PAD_FORMAT "%08lx"
 #endif
 
 #define FIXNUM_FORMAT "%ld"
diff --git a/vm/os-windows.hpp b/vm/os-windows.hpp
index 5422216593..27e2775289 100755
--- a/vm/os-windows.hpp
+++ b/vm/os-windows.hpp
@@ -22,14 +22,14 @@ typedef wchar_t vm_char;
 #define FSEEK fseek
 
 #ifdef WIN64
-	#define cell_FORMAT "%Iu"
-	#define cell_HEX_FORMAT "%Ix"
-	#define cell_HEX_PAD_FORMAT "%016Ix"
+	#define CELL_FORMAT "%Iu"
+	#define CELL_HEX_FORMAT "%Ix"
+	#define CELL_HEX_PAD_FORMAT "%016Ix"
 	#define FIXNUM_FORMAT "%Id"
 #else
-	#define cell_FORMAT "%lu"
-	#define cell_HEX_FORMAT "%lx"
-	#define cell_HEX_PAD_FORMAT "%08lx"
+	#define CELL_FORMAT "%lu"
+	#define CELL_HEX_FORMAT "%lx"
+	#define CELL_HEX_PAD_FORMAT "%08lx"
 	#define FIXNUM_FORMAT "%ld"
 #endif
 
diff --git a/vm/utilities.cpp b/vm/utilities.cpp
index df5c09847d..37fe28948e 100755
--- a/vm/utilities.cpp
+++ b/vm/utilities.cpp
@@ -32,17 +32,17 @@ void print_string(const char *str)
 
 void print_cell(cell x)
 {
-	printf(cell_FORMAT,x);
+	printf(CELL_FORMAT,x);
 }
 
 void print_cell_hex(cell x)
 {
-	printf(cell_HEX_FORMAT,x);
+	printf(CELL_HEX_FORMAT,x);
 }
 
 void print_cell_hex_pad(cell x)
 {
-	printf(cell_HEX_PAD_FORMAT,x);
+	printf(CELL_HEX_PAD_FORMAT,x);
 }
 
 void print_fixnum(fixnum x)
@@ -53,7 +53,7 @@ void print_fixnum(fixnum x)
 cell read_cell_hex()
 {
 	cell cell;
-	if(scanf(cell_HEX_FORMAT,&cell) < 0) exit(1);
+	if(scanf(CELL_HEX_FORMAT,&cell) < 0) exit(1);
 	return cell;
 };