diff --git a/vm/debug.cpp b/vm/debug.cpp
index bb3a8b0ce5..914743fc67 100755
--- a/vm/debug.cpp
+++ b/vm/debug.cpp
@@ -377,9 +377,10 @@ void factor_vm::factorbug()
 		char cmd[1024];
 
 		std::cout << "READY\n";
-		fflush(stdout);
+		std::cout.flush();
 
-		if(scanf("%1000s",cmd) <= 0)
+		std::cin >> std::setw(1024) >> cmd >> std::setw(0); 
+		if(!std::cin.good())
 		{
 			if(!seen_command)
 			{
@@ -402,7 +403,10 @@ void factor_vm::factorbug()
 		if(strcmp(cmd,"d") == 0)
 		{
 			cell addr = read_cell_hex();
-			if(scanf(" ") < 0) break;
+			if (std::cin.peek() == ' ')
+				std::cin.ignore();
+
+			if(!std::cin.good()) break;
 			cell count = read_cell_hex();
 			dump_memory(addr,addr+count);
 		}
diff --git a/vm/master.hpp b/vm/master.hpp
index b8ababeb2d..d2b9a5f709 100755
--- a/vm/master.hpp
+++ b/vm/master.hpp
@@ -20,6 +20,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <wchar.h>
 
 /* C++ headers */
 #include <algorithm>
@@ -27,6 +28,7 @@
 #include <set>
 #include <vector>
 #include <iostream>
+#include <iomanip>
 
 #define FACTOR_STRINGIZE(x) #x
 
diff --git a/vm/os-macosx.mm b/vm/os-macosx.mm
index c5377be8ef..93b4edd06a 100644
--- a/vm/os-macosx.mm
+++ b/vm/os-macosx.mm
@@ -17,7 +17,7 @@ void early_init(void)
 	Gestalt(gestaltSystemVersion,&version);
 	if(version < 0x1050)
 	{
-		printf("Factor requires Mac OS X 10.5 or later.\n");
+		std::cout << "Factor requires Mac OS X 10.5 or later.\n";
 		exit(1);
 	}
 
diff --git a/vm/os-unix.hpp b/vm/os-unix.hpp
index 54e9d068ef..c774707a76 100644
--- a/vm/os-unix.hpp
+++ b/vm/os-unix.hpp
@@ -27,8 +27,6 @@ typedef char symbol_char;
 #define FTELL ftello
 #define FSEEK fseeko
 
-#define CELL_HEX_FORMAT "%lx"
-
 #define OPEN_READ(path) fopen(path,"rb")
 #define OPEN_WRITE(path) fopen(path,"wb")
 
diff --git a/vm/os-windows.cpp b/vm/os-windows.cpp
index 1ff1b174b5..67f48bc99e 100755
--- a/vm/os-windows.cpp
+++ b/vm/os-windows.cpp
@@ -57,7 +57,10 @@ BOOL factor_vm::windows_stat(vm_char *path)
 
 void factor_vm::windows_image_path(vm_char *full_path, vm_char *temp_path, unsigned int length)
 {
-	SNWPRINTF(temp_path, length-1, L"%s.image", full_path); 
+	wcsncpy(temp_path, full_path, length - 1);
+        unsigned full_path_len = wcslen(full_path);
+	if (full_path_len < length - 1)
+		wcsncat(temp_path, L".image", length - full_path_len - 1);
 	temp_path[length - 1] = 0;
 }
 
@@ -74,7 +77,10 @@ const vm_char *factor_vm::default_image_path()
 	if((ptr = wcsrchr(full_path, '.')))
 		*ptr = 0;
 
-	SNWPRINTF(temp_path, MAX_UNICODE_PATH-1, L"%s.image", full_path); 
+	wcsncpy(temp_path, full_path, MAX_UNICODE_PATH - 1);
+        unsigned full_path_len = wcslen(full_path);
+	if (full_path_len < length - 1)
+		wcsncat(temp_path, L".image", MAX_UNICODE_PATH - full_path_len - 1);
 	temp_path[MAX_UNICODE_PATH - 1] = 0;
 
 	return safe_strdup(temp_path);
diff --git a/vm/os-windows.hpp b/vm/os-windows.hpp
index ad8a9907a7..03dec4bb02 100755
--- a/vm/os-windows.hpp
+++ b/vm/os-windows.hpp
@@ -23,18 +23,10 @@ typedef wchar_t vm_char;
 	#define FTELL ftell
 	#define FSEEK fseek
 	#define SNPRINTF _snprintf
-	#define SNWPRINTF _snwprintf
 #else
 	#define FTELL ftello64
 	#define FSEEK fseeko64
 	#define SNPRINTF snprintf
-	#define SNWPRINTF snwprintf
-#endif
-
-#ifdef WIN64
-	#define CELL_HEX_FORMAT "%Ix"
-#else
-	#define CELL_HEX_FORMAT "%lx"
 #endif
 
 #define OPEN_READ(path) _wfopen((path),L"rb")
diff --git a/vm/run.cpp b/vm/run.cpp
index 605fd9b725..00d15fc42a 100755
--- a/vm/run.cpp
+++ b/vm/run.cpp
@@ -11,7 +11,13 @@ void factor_vm::primitive_exit()
 void factor_vm::primitive_nano_count()
 {
 	u64 nanos = nano_count();
-	if(nanos < last_nano_count) critical_error("Monotonic counter decreased",0);
+	if(nanos < last_nano_count) {
+            std::cout << "Monotonic counter decreased from 0x";
+            std::cout << std::hex << last_nano_count;
+            std::cout << " to 0x" << nanos << "." << std::dec << "\n";
+            std::cout << "Please report this error.\n";
+            current_vm()->factorbug();
+	}
 	last_nano_count = nanos;
 	ctx->push(from_unsigned_8(nanos));
 }
diff --git a/vm/utilities.cpp b/vm/utilities.cpp
index 3e976d0619..11d3de78cc 100755
--- a/vm/utilities.cpp
+++ b/vm/utilities.cpp
@@ -14,7 +14,8 @@ vm_char *safe_strdup(const vm_char *str)
 cell read_cell_hex()
 {
 	cell cell;
-	if(scanf(CELL_HEX_FORMAT,&cell) < 0) exit(1);
+	std::cin >> std::hex >> cell >> std::dec;
+	if(!std::cin.good()) exit(1);
 	return cell;
 }