diff --git a/.ci/compile.sh b/.ci/compile.sh
index f20432893..c8c1e539b 100755
--- a/.ci/compile.sh
+++ b/.ci/compile.sh
@@ -345,13 +345,45 @@ if [[ $MAKE_PACKAGE ]]; then
     else
       echo "Inspecting $package"
       # Fail the build if the installer contains any path left behind by the MSBuild or
-      # Qt AUTOMOC tooling (build-tree artifacts must live in the build dir, not the install)
+      # Qt AUTOMOC tooling (build-tree artifacts must live in the build dir, not in the install)
       if "$seven_zip" l "$package" |
         grep -E "_autogen|\.dir[\\/]|\.tlog|(^|[\\/])x64[\\/]|(^|[\\/])\.qt[\\/]|(^|[\\/])\.qsb[\\/]|(^|[\\/])\.lupdate[\\/]|CMakeFiles"; then
         echo "::error file=$0::Installer contains build-tree artifacts"
         exit 1
       fi
       echo "Installer content is clean"
+
+      # Fail the build if the installer is missing a Qt runtime the applications
+      # link against. The DLLs reach the package by globbing every *.dll out of
+      # the build output directories, so a module the client links statically
+      # (Qt6Multimedia.dll, Qt6QuickWidgets.dll) can be left out without anything
+      # else noticing, and the only symptom is a client that refuses to start
+      # after an update. required-qt-runtime.txt is written by the top level
+      # CMakeLists.txt from the same module list the targets are built against.
+      if [[ ! -f required-qt-runtime.txt ]]; then
+        echo "::error file=$0::required-qt-runtime.txt not found in the build dir, cannot verify the Qt runtime"
+        exit 1
+      fi
+      # Normalize the archive's own separators to / so the entries below can be
+      # compared as exact relative paths, and use -xF so a '.' in a DLL name is
+      # never a wildcard.
+      installer_paths="$("$seven_zip" l -slt "$package" | sed -n 's/^Path = //p' | sed 's|\\|/|g')"
+      missing=""
+      checked=0
+      while IFS= read -r entry; do
+        if [[ -z $entry || $entry == \#* ]]; then
+          continue
+        fi
+        checked=$((checked + 1))
+        if ! grep -qxF "$entry" <<<"$installer_paths"; then
+          missing+=" $entry"
+        fi
+      done <required-qt-runtime.txt
+      if [[ -n $missing ]]; then
+        echo "::error file=$0::Installer is missing required Qt runtime files:$missing"
+        exit 1
+      fi
+      echo "Installer contains the full Qt runtime ($checked files)"
     fi
     echo "::endgroup::"
   fi
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 293e25dd9..a297d60e6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -326,6 +326,30 @@ elseif(WIN32)
   # Configure file with custom definitions for NSIS.
   configure_file("${COCKATRICE_CMAKE_PATH}/NSIS.definitions.nsh.in" "${PROJECT_BINARY_DIR}/NSIS.definitions.nsh")
 
+  # Every Qt module the configured applications link against, as the DLL names a
+  # Windows install has to contain, plus the platform plugin without which the
+  # client cannot start. .ci/compile.sh reads this and fails the build when the
+  # packaged installer is missing one of them.
+  #
+  # The DLLs are deployed by globbing every *.dll out of the build output
+  # directories, so nothing but luck decides whether a module the client links
+  # statically - Qt6Multimedia.dll, Qt6QuickWidgets.dll - reaches the installer at
+  # all. A DLL that is missing from the package only surfaces on a user's machine,
+  # after an update has already replaced their install, as "The code execution
+  # cannot proceed because Qt6Multimedia.dll was not found" or as a missing
+  # procedure entry point in a Qt6QuickWidgets.dll left over from the previous
+  # version. Assert it while the installer is still being built instead.
+  set(_required_qt_runtime "")
+  foreach(_qt_module IN LISTS SERVATRICE_QT_MODULES COCKATRICE_QT_MODULES ORACLE_QT_MODULES)
+    string(REGEX REPLACE "^Qt6::" "" _qt_component "${_qt_module}")
+    list(APPEND _required_qt_runtime "Qt6${_qt_component}.dll")
+  endforeach()
+  list(APPEND _required_qt_runtime "Plugins/platforms/qwindows.dll")
+  list(REMOVE_DUPLICATES _required_qt_runtime)
+  list(SORT _required_qt_runtime)
+  string(REPLACE ";" "\n" _required_qt_runtime "${_required_qt_runtime}")
+  file(WRITE "${PROJECT_BINARY_DIR}/required-qt-runtime.txt" "${_required_qt_runtime}\n")
+
   # include vcredist into the package; NSIS will take care of running it
   if(VCREDISTRUNTIME_FOUND)
     install(FILES "${VCREDISTRUNTIME_FILE}" DESTINATION ./)