Index: include/ruby/win32.h
===================================================================
--- include/ruby/win32.h	(revision 19901)
+++ include/ruby/win32.h	(working copy)
@@ -248,6 +248,12 @@
 extern int rb_w32_vsnprintf(char *, size_t, const char *, va_list);
 extern int rb_w32_snprintf(char *, size_t, const char *, ...);
 
+#if (defined(_MSC_VER) && defined(_DLL)) || defined(__MSVCRT__)
+#undef HAVE_VSNPRINTF
+#define _vsnprintf BSD_vsnprintf
+extern int BSD_vsnprintf(char *, size_t, const char *, va_list);
+#endif
+
 extern int chown(const char *, int, int);
 extern int link(const char *, const char *);
 extern int gettimeofday(struct timeval *, struct timezone *);
Index: numeric.c
===================================================================
--- numeric.c	(revision 19901)
+++ numeric.c	(working copy)
@@ -530,12 +530,12 @@
     else if(isnan(value))
 	return rb_usascii_str_new2("NaN");
 
-    sprintf(buf, "%#.15g", value); /* ensure to print decimal point */
+    snprintf(buf, 32, "%#.15g", value); /* ensure to print decimal point */
     if (!(e = strchr(buf, 'e'))) {
 	e = buf + strlen(buf);
     }
     if (!ISDIGIT(e[-1])) { /* reformat if ended with decimal point (ex 111111111111111.) */
-	sprintf(buf, "%#.14e", value);
+	snprintf(buf, 32, "%#.14e", value);
 	if (!(e = strchr(buf, 'e'))) {
 	    e = buf + strlen(buf);
 	}
@@ -1548,7 +1548,7 @@
 	    char buf[24];
 	    char *s;
 
-	    sprintf(buf, "%-.10g", RFLOAT_VALUE(val));
+	    snprintf(buf, 24, "%-.10g", RFLOAT_VALUE(val));
 	    if ((s = strchr(buf, ' ')) != 0) *s = '\0';
 	    rb_raise(rb_eRangeError, "float %s out of range of integer", buf);
 	}
@@ -1694,7 +1694,7 @@
 	    char buf[24];
 	    char *s;
 
-	    sprintf(buf, "%-.10g", RFLOAT_VALUE(val));
+	    snprintf(buf, 24, "%-.10g", RFLOAT_VALUE(val));
 	    if ((s = strchr(buf, ' ')) != 0) *s = '\0';
 	    rb_raise(rb_eRangeError, "float %s out of range of long long", buf);
 	}
Index: sprintf.c
===================================================================
--- sprintf.c	(revision 19901)
+++ sprintf.c	(working copy)
@@ -1018,7 +1018,7 @@
 		need += 20;
 
 		CHECK(need);
-		sprintf(&buf[blen], fbuf, fval);
+		snprintf(&buf[blen], need, fbuf, fval);
 		blen += strlen(&buf[blen]);
 	    }
 	    break;
Index: missing/vsnprintf.c
===================================================================
--- missing/vsnprintf.c	(revision 19901)
+++ missing/vsnprintf.c	(working copy)
@@ -781,8 +781,10 @@
 			flags |= FPT;
 			cp = cvt(_double, prec, flags, &softsign,
 				&expt, ch, &ndig);
+			if ((ch == 'e' || ch == 'E') && ndig < prec)
+				ndig = prec;
 			if (ch == 'g' || ch == 'G') {
-				if (expt <= -4 || expt > prec)
+				if (expt <= -4 || (expt > prec && expt > 1))
 					ch = (ch == 'g') ? 'e' : 'E';
 				else
 					ch = 'g';
@@ -798,7 +800,9 @@
 					size = expt;
 					if (prec || flags & ALT)
 						size += prec + 1;
-				} else	/* "0.X" */
+				} else if (!prec) /* "0" */
+				  size = 1;
+				else	/* "0.X" */
 					size = prec + 2;
 			} else if (expt >= ndig) {	/* fixed g fmt */
 				size = expt;
@@ -1008,13 +1012,15 @@
 			if (ch >= 'f') {	/* 'f' or 'g' */
 				if (_double == 0) {
 				/* kludge for __dtoa irregularity */
-					if (prec == 0 ||
+					if (ndig <= 1 &&
 					    (flags & ALT) == 0) {
 						PRINT("0", 1);
 					} else {
 						PRINT("0.", 2);
 						PAD(ndig - 1, zeroes);
 					}
+				} else if (expt == 0 && ndig == 0 && (flags & ALT) == 0) {
+					PRINT("0", 1);
 				} else if (expt <= 0) {
 					PRINT("0.", 2);
 					PAD(-expt, zeroes);
@@ -1036,7 +1042,14 @@
 					ox[1] = '.';
 					PRINT(ox, 2);
 					if (_double || flags & ALT == 0) {
-						PRINT(cp, ndig-1);
+						int i;
+						for (i = 0; i < ndig - 1; i++) {
+							if (cp[i] == '\0')
+								break;
+						}
+						PRINT(cp, i);
+						if (i < ndig - 1)
+							PAD(ndig - 1 - i, zeroes);
 					} else	/* 0.[0..] */
 						/* __dtoa irregularity */
 						PAD(ndig - 1, zeroes);
@@ -1141,7 +1154,11 @@
 
 #ifndef HAVE_VSNPRINTF
 int
+#if (defined(_MSC_VER) && defined(_DLL)) || defined(__MSVCRT__)
+BSD_vsnprintf(str, n, fmt, ap)
+#else
 vsnprintf(str, n, fmt, ap)
+#endif
 	char *str;
 	size_t n;
 	const char *fmt;