diff --git a/lib/forge.func b/lib/forge.func
index 291567c..3b33944 100644
--- a/lib/forge.func
+++ b/lib/forge.func
@@ -1556,9 +1556,10 @@ _forge_release_json() {
     # The maintainer's own "latest" marking beats anything the tag strings can
     # tell us: it is what separates a release line from nightlies, betas and a
     # second product's tags in the same repo, none of which are reliably
-    # flagged prerelease. Only the unfiltered, stable case can use it.
-    if [[ -z "$tag_prefix" && "${GH_INCLUDE_PRERELEASE:-0}" != "1" ]] &&
-      _forge_designated_release "$forge" "$base" "$repo_path" "$out"; then
+    # flagged prerelease. Only the stable case can use it; a tag prefix only when that release carries it.
+    if [[ "${GH_INCLUDE_PRERELEASE:-0}" != "1" ]] &&
+      _forge_designated_release "$forge" "$base" "$repo_path" "$out" &&
+      [[ -z "$tag_prefix" || "$(jq -r '.tag_name // ""' "$out" 2>/dev/null)" == "$tag_prefix"* ]]; then
       [[ "$forge" == "github" ]] && _forge_keep_raw "$out"
       return 0
     fi
diff --git a/tests/forge-release-json.sh b/tests/forge-release-json.sh
index 2cf4cc0..ecc1082 100644
--- a/tests/forge-release-json.sh
+++ b/tests/forge-release-json.sh
@@ -100,6 +100,19 @@ expect "the designated release still resolves" 0 "$?"
 expect "the designated release is used" v3.0.0 "$(jq -r .tag_name "$OUT")"
 expect "only one request was needed" 1 "$(grep -c curl "$CALLS")"
 
+prefixed() {
+  : >"$CALLS"
+  : >"$OUT"
+  _forge_release_json github maplibre/martin latest "martin-v" "$OUT"
+}
+MOCK_LATEST_CODE=200 MOCK_LATEST_BODY='{"tag_name":"martin-v1.16.1","draft":false,"prerelease":false}' \
+  MOCK_BODY='[{"tag_name":"mbtiles-v0.15.0","draft":false,"prerelease":false}]' prefixed
+expect "a prefix takes the designated release when it carries the prefix" martin-v1.16.1 "$(jq -r .tag_name "$OUT")"
+expect "without asking for the list" 1 "$(grep -c curl "$CALLS")"
+MOCK_LATEST_CODE=200 MOCK_LATEST_BODY='{"tag_name":"mbtiles-v0.15.0","draft":false,"prerelease":false}' \
+  MOCK_BODY='[{"tag_name":"martin-v1.16.1","draft":false,"prerelease":false},{"tag_name":"mbtiles-v0.15.0","draft":false,"prerelease":false}]' prefixed
+expect "another product's designated release falls back to the list" martin-v1.16.1 "$(jq -r .tag_name "$OUT")"
+
 # databasement: without jq the prefixed lookup read "no tags" and built a URL without a version.
 (
   ensure_dependencies() {