diff --git a/ext/mbstring/mbstring.c b/ext/mbstring/mbstring.c
index faa21b11a0f7..8026b69399fd 100644
--- a/ext/mbstring/mbstring.c
+++ b/ext/mbstring/mbstring.c
@@ -4490,6 +4490,9 @@ static int _php_mbstr_parse_mail_headers(HashTable *ht, const char *str, size_t
 
 								zend_string_release_ex(fld_name, 0);
 							}
+							else if (fld_name != NULL) {
+								zend_string_release_ex(fld_name, 0);
+							}
 
 							fld_name = fld_val = NULL;
 							token = (char*)ps;
@@ -4535,6 +4538,9 @@ static int _php_mbstr_parse_mail_headers(HashTable *ht, const char *str, size_t
 
 			zend_string_release_ex(fld_name, 0);
 		}
+		else if (fld_name != NULL) {
+			zend_string_release_ex(fld_name, 0);
+		}
 	}
 	return state;
 }