diff --git a/lib/core/settings.py b/lib/core/settings.py
index ee6ccc6f7..d8340153e 100644
--- a/lib/core/settings.py
+++ b/lib/core/settings.py
@@ -403,7 +403,7 @@ ITOA64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
 DUMMY_SQL_INJECTION_CHARS = ";()'"
 
 # Simple check against dummy users
-DUMMY_USER_INJECTION = r"(?i)[^\w](AND|OR)\s+[^\s]+[=><]|\bUNION\b.+\bSELECT\b"
+DUMMY_USER_INJECTION = r"(?i)[^\w](AND|OR)\s+[^\s]+[=><]|\bUNION\b.+\bSELECT\b|\A-\d+\Z"
 
 # Extensions skipped by crawler
 CRAWL_EXCLUDE_EXTENSIONS = ("gif", "jpg", "jpeg", "image", "jar", "tif", "bmp", "war", "ear", "mpg", "mpeg", "wmv", "mpeg", "scm", "iso", "dmp", "dll", "cab", "so", "avi", "mkv", "bin", "iso", "tar", "png", "pdf", "ps", "wav", "mp3", "mp4", "au", "aiff", "aac", "zip", "rar", "7z", "gz", "flv", "mov", "doc", "docx", "xls", "dot", "dotx", "xlt", "xlsx", "ppt", "pps", "pptx")