diff --git a/ccan/opt/helpers.c b/ccan/opt/helpers.c
index 8d0ac547..6b7218a0 100644
--- a/ccan/opt/helpers.c
+++ b/ccan/opt/helpers.c
@@ -11,7 +11,7 @@
 /* FIXME: asprintf module? */
 static char *arg_bad(const char *fmt, const char *arg)
 {
-	char *str = malloc(strlen(fmt) + strlen(arg));
+	char *str = (char *)malloc(strlen(fmt) + strlen(arg));
 	sprintf(str, fmt, arg);
 	return str;
 }
@@ -74,7 +74,11 @@ char *opt_set_floatval(const char *arg, float *f)
 	char *endp;
 
 	errno = 0;
+#if (_MSC_VER >= 1800)
 	*f = strtof(arg, &endp);
+#else
+	*f = strtod(arg, &endp);
+#endif
 	if (*endp || !arg[0])
 		return arg_bad("'%s' is not a number", arg);
 	if (errno)
diff --git a/ccan/opt/opt.c b/ccan/opt/opt.c
index 9bc34d92..08f8d2a7 100644
--- a/ccan/opt/opt.c
+++ b/ccan/opt/opt.c
@@ -152,7 +152,7 @@ static void check_opt(const struct opt_table *entry)
 
 static void add_opt(const struct opt_table *entry)
 {
-	opt_table = realloc(opt_table, sizeof(opt_table[0]) * (opt_count+1));
+	opt_table = (struct opt_table *)realloc(opt_table, sizeof(opt_table[0]) * (opt_count + 1));
 	opt_table[opt_count++] = *entry;
 }
 
@@ -202,19 +202,19 @@ bool opt_parse(int *argc, char *argv[], void (*errlog)(const char *fmt, ...))
 	int ret;
 	unsigned offset = 0;
 	
-	#ifdef WIN32
+#if defined(WIN32) && !defined(_MSC_VER)
 	char *original_argv0 = argv[0];
 	argv[0] = (char*)basename(argv[0]);
-	#endif
+#endif
 
 	/* This helps opt_usage. */
 	opt_argv0 = argv[0];
 
 	while ((ret = parse_one(argc, argv, &offset, errlog)) == 1);
 	
-	#ifdef WIN32
+#if defined(WIN32) && !defined(_MSC_VER)
 	argv[0] = original_argv0;
-	#endif
+#endif
 
 	/* parse_one returns 0 on finish, -1 on error */
 	return (ret == 0);
@@ -249,7 +249,7 @@ void opt_log_stderr_exit(const char *fmt, ...)
 
 char *opt_invalid_argument(const char *arg)
 {
-	char *str = malloc(sizeof("Invalid argument '%s'") + strlen(arg));
+	char *str = (char *)malloc(sizeof("Invalid argument '%s'") + strlen(arg));
 	sprintf(str, "Invalid argument '%s'", arg);
 	return str;
 }
diff --git a/ccan/opt/usage.c b/ccan/opt/usage.c
index 4d784bc2..108e9b89 100644
--- a/ccan/opt/usage.c
+++ b/ccan/opt/usage.c
@@ -6,7 +6,7 @@
 #include "private.h"
 
 /* We only use this for pointer comparisons. */
-const char opt_hidden[1];
+const char opt_hidden[1] = { 0 };
 
 static unsigned write_short_options(char *str)
 {
@@ -33,7 +33,7 @@ char *opt_usage(const char *argv0, const char *extra)
 		for (i = 0; i < opt_count; i++) {
 			if (opt_table[i].cb == (void *)opt_usage_and_exit
 			    && opt_table[i].u.carg) {
-				extra = opt_table[i].u.carg;
+				extra = (const char *)opt_table[i].u.carg;
 				break;
 			}
 		}
@@ -61,7 +61,7 @@ char *opt_usage(const char *argv0, const char *extra)
 		}
 	}
 
-	p = ret = malloc(len);
+	p = ret = (char *)malloc(len);
 	if (!ret)
 		return NULL;