diff --git a/docker/bin/build-reference-cli b/docker/bin/build-reference-cli
index c7356f27..b86ddee9 100755
--- a/docker/bin/build-reference-cli
+++ b/docker/bin/build-reference-cli
@@ -36,10 +36,45 @@ if [ -z "$src" ]; then
 fi
 [ -n "$src" ] || { echo "build-reference-cli: no checkout for rev $rev" >&2; exit 1; }
 
+# Build into a target directory KEYED BY THE REVISION.
+#
+# This is not tidiness. Sharing one target dir across pins silently served a
+# stale binary: after the pin moved 8b6dbcf -> 5414db3, cargo reported
+# "Finished in 0.13s" and left in place a `sylpheed-cli` built from the OLD
+# decoders. `screen list` still worked, so the old check passed, and the
+# reference renderer this whole project verifies against was a revision behind
+# for three consecutive diff runs. A per-rev tree cannot do that: a new pin has
+# no artifacts to reuse.
 echo "build-reference-cli: building sylpheed-cli from $rev"
-cargo build --release --manifest-path "$src/Cargo.toml" -p sylpheed-cli
+tree="$CARGO_TARGET_DIR/reference-cli/$rev"
+CARGO_TARGET_DIR="$tree" cargo build --release --manifest-path "$src/Cargo.toml" -p sylpheed-cli
 
-out="$CARGO_TARGET_DIR/release/sylpheed-cli"
-"$out" screen list "${SYLPHEED_DISC:-/disc}/dat/GP_TITLE.pak" >/dev/null \
+stable="$CARGO_TARGET_DIR/reference-cli/sylpheed-cli"
+mkdir -p "$(dirname "$stable")"
+cp -f "$tree/release/sylpheed-cli" "$stable"
+
+"$stable" screen list "${SYLPHEED_DISC:-/disc}/dat/GP_TITLE.pak" >/dev/null \
   || { echo "build-reference-cli: built, but 'screen list' failed" >&2; exit 1; }
-echo "build-reference-cli: $out  (rev $rev, 'screen' subcommand present)"
+
+# And check the binary is actually the pinned code, not merely a working one.
+# `screen info` prints each element's resting placement, which is decoder
+# output; if this disagrees with what the exporter wrote from the same pin, the
+# two halves of the verification are not the same revision and every diff below
+# is meaningless. Compare rather than assert a value, so this stays true when
+# the pin moves again.
+if [ -f "${PROJECT_DIR:-/work}/export/screens/title/main_menu.json" ]; then
+  cli_rest=$("$stable" screen info "${SYLPHEED_DISC:-/disc}/dat/GP_TITLE.pak" --build 5 \
+             | sed -n 's/.*ptframe1\.t32.*rest (\([0-9]*\),\([0-9]*\)).*/\1,\2/p')
+  exp_rest=$(python3 -c '
+import json,sys
+d=json.load(open(sys.argv[1]))
+e=next(e for e in d["elements"] if e["id"]=="ptframe1")
+print("%d,%d" % tuple(e["rest"]["pos"]))' "${PROJECT_DIR:-/work}/export/screens/title/main_menu.json")
+  if [ "$cli_rest" != "$exp_rest" ]; then
+    echo "build-reference-cli: STALE OR MISMATCHED BINARY" >&2
+    echo "  the CLI resolves ptframe1 rest to ($cli_rest) but export/ says ($exp_rest)." >&2
+    echo "  Both should come from rev $rev. Delete $tree and rebuild." >&2
+    exit 1
+  fi
+fi
+echo "build-reference-cli: $stable  (rev $rev, agrees with export/ on ptframe1)"
diff --git a/tools/verify-screen b/tools/verify-screen
index 3fd2181e..6ca45069 100755
--- a/tools/verify-screen
+++ b/tools/verify-screen
@@ -35,7 +35,10 @@
 set -euo pipefail
 cd "${PROJECT_DIR:-/work}"
 
-CLI="${SYLPHEED_CLI:-${CARGO_TARGET_DIR:-/sylph-home/port/target-container}/release/sylpheed-cli}"
+# `reference-cli/`, not `release/`: the reference binary is built per pinned
+# revision so a pin change cannot silently reuse the previous revision's build.
+# See docker/bin/build-reference-cli.
+CLI="${SYLPHEED_CLI:-${CARGO_TARGET_DIR:-/sylph-home/port/target-container}/reference-cli/sylpheed-cli}"
 DISC="${SYLPHEED_DISC:-/disc}"
 OUT="${OUT:-${TMPDIR:-/tmp}/verify-screen}"
 export DISPLAY="${DISPLAY:-:97}"