diff --git a/amxmodx/format.cpp b/amxmodx/format.cpp
index 0b39384a..4bc85a7a 100644
--- a/amxmodx/format.cpp
+++ b/amxmodx/format.cpp
@@ -390,15 +390,21 @@ reswitch:
 			}
 		case '%':
 			*buf_p++ = static_cast<D>(ch);
+			if (!llen)
+				goto done;
 			llen--;
 			break;
 		case '\0':
 			*buf_p++ = static_cast<D>('%');
+			if (!llen)
+				goto done;
 			llen--;
 			goto done;
 			break;
 		default:
 			*buf_p++ = static_cast<D>(ch);
+			if (!llen)
+				goto done;
 			llen--;
 			break;
 		}