diff --git a/.github/workflows/desktop-build.yml b/.github/workflows/desktop-build.yml
index 77cba2455..9aafedd29 100644
--- a/.github/workflows/desktop-build.yml
+++ b/.github/workflows/desktop-build.yml
@@ -248,10 +248,10 @@ jobs:
       #   Debian 13            Release + suite     625 MB               800M
       #   Fedora 45 debug      Debug + suite       660 MB               850M
       #   Fedora 45 release    Release + package   614 MB               800M
-      #   Windows 10           Release + package   1.2 GB working set   1300M
+      #   Windows 10           Release + package   890 MB working set   950M
       #
-      # That is 4.6 GB of bounds; what lands in the quota is 4.3 GB of compiler cache,
-      # 2.97 GB stored by the Linux legs and 1.30 GB by Windows, for 8.4 GB of 10 in total.
+      # That is 4.25 GB of bounds; what lands in the quota is 3.9 GB of compiler cache,
+      # 2.97 GB stored by the Linux legs and 0.95 GB by Windows, for 8.1 GB of 10 in total.
       # So only legs worth their share get one. A leg keeps no cache when it duplicates
       # another leg's coverage (Ubuntu 26.04 behind Debian 13's Release + suite; the macOS
       # legs behind the Linux ones) or finishes well inside the Windows leg (Servatrice
@@ -680,7 +680,7 @@ jobs:
             qt_modules: qtimageformats qtmultimedia qtshadertools qtwebsockets
             type: Release
             ccache_eviction_age: 7d
-            ccache_size: 1300M    # Release plus the package: 1.2 GB working set at /Z7
+            ccache_size: 950M    # Release plus the package: 890 MB working set without /Z7
             use_ccache: 1
             # Scope is named after the vs2026 toolchain, not the generator: the
             # ABI hash covers cl.exe, which is identical, so this leg keeps