diff --git a/docs/architecture/adr-0036-scan-uploads-with-clamav.md b/docs/architecture/adr-0036-scan-uploads-with-clamav.md
index 62d5f92..90947bc 100644
--- a/docs/architecture/adr-0036-scan-uploads-with-clamav.md
+++ b/docs/architecture/adr-0036-scan-uploads-with-clamav.md
@@ -33,8 +33,10 @@ and that makes it an ADR (CLAUDE.md §14).
    **no NuGet package** for it (nClam and similar).
 4. **Fail closed:** if clamd can't be reached, the upload is refused (503). Nothing is
    stored and the document wait stays open. We never store an unscanned file.
-5. **Type check:** content must start with `%PDF-`. This refuses a renamed executable
-   before the scan, and it costs nothing.
+5. **Type check:** content must also start with `%PDF-`, checked **after** the scan.
+   clamd matches EICAR (and many real signatures) only at the start of a file, so a type
+   check in front of the scan would report malware as merely "not a PDF". The check also
+   refuses a renamed non-PDF that is clean.
 
 ## Consequences