diff --git a/NEWS b/NEWS
index 78abcbc5e50c9..cb81b008695cb 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,7 @@ PHP                                                                        NEWS
 - Added stream filter support to mcrypt extension (ported from 
   mcrypt_filter). (Stas)
 
+- Fixed bug #51237 (milter SAPI crash on startup). (igmar at palsenberg dot com)
 - Fixed bug #51213 (pdo_mssql is trimming value of the money column). (Ilia, 
   alexr at oplot dot com)
 - Fixed bug #51190 (ftp_put() returns false when transfer was successful).  
diff --git a/sapi/milter/php_milter.c b/sapi/milter/php_milter.c
index 6c07c018e2cba..11724c425ca06 100644
--- a/sapi/milter/php_milter.c
+++ b/sapi/milter/php_milter.c
@@ -92,7 +92,7 @@ extern char *ap_php_optarg;
 extern int ap_php_optind;
 
 static int flag_debug=0;
-static char *filename;
+static char *filename = NULL;
 
 /* per thread */
 ZEND_BEGIN_MODULE_GLOBALS(milter)
@@ -127,6 +127,11 @@ static int mlfi_init()
 	/* disable headers */
 	SG(headers_sent) = 1;
 	SG(request_info).no_headers = 1;
+	 
+	if (filename == NULL) {
+		php_printf("No input file specified");
+		return SMFIS_TEMPFAIL;
+	}
 
 	if (!(file_handle.handle.fp = VCWD_FOPEN(filename, "rb"))) {
 		php_printf("Could not open input file: %s\n", filename);
@@ -189,6 +194,11 @@ static sfsistat	mlfi_connect(SMFICTX *ctx, char *hostname, _SOCK_ADDR *hostaddr)
 	SG(headers_sent) = 1;
 	SG(request_info).no_headers = 1;
 	
+	if (filename == NULL) {
+		php_printf("No input file specified");
+		return SMFIS_TEMPFAIL;
+	}
+	
 	if (!(file_handle.handle.fp = VCWD_FOPEN(filename, "rb"))) {
 		php_printf("Could not open input file: %s\n", filename);
 		return SMFIS_TEMPFAIL;