diff --git a/stack.yaml b/stack.yaml
index f6db01a228..c88035cee7 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -15,3 +15,6 @@ extra-deps:
   - jose-jwt-0.10.0
   - postgresql-libpq-0.10.1.0
   - streaming-commons-0.2.3.1
+
+  # fix build with GCC 15-ish; https://github.com/gregorycollins/hashtables/issues/98 for details
+  - hashtables-1.4.2@sha256:4940cab94a15d469845ccf5225f9cb3d354c15e8127ebb58425c8b681f7721d9,10386
diff --git a/stack.yaml.lock b/stack.yaml.lock
index b3d989f1d6..ae2cbfd7ce 100644
--- a/stack.yaml.lock
+++ b/stack.yaml.lock
@@ -46,6 +46,13 @@ packages:
       size: 2374
   original:
     hackage: streaming-commons-0.2.3.1
+- completed:
+    hackage: hashtables-1.4.2@sha256:4940cab94a15d469845ccf5225f9cb3d354c15e8127ebb58425c8b681f7721d9,10386
+    pantry-tree:
+      sha256: 65107f0c970351b971ea1f676a5e00b61e37c298a4c83c867d937f2a774501eb
+      size: 2895
+  original:
+    hackage: hashtables-1.4.2@sha256:4940cab94a15d469845ccf5225f9cb3d354c15e8127ebb58425c8b681f7721d9,10386
 snapshots:
 - completed:
     sha256: 238fa745b64f91184f9aa518fe04bdde6552533d169b0da5256670df83a0f1a9