diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 00000000..4a67e8e0
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,9 @@
+# Byte-exact fixtures and assets: never convert line endings (Windows checkouts use
+# core.autocrlf=true, which changes the signed bytes of a PDF and breaks its signature).
+*.pdf binary
+*.p12 binary
+*.pem -text
+*.pfb binary
+*.ttf binary
+*.icc binary
+*.png binary