diff --git a/indra/cmake/BuildPackagesInfo.cmake b/indra/cmake/BuildPackagesInfo.cmake
index 0f574ee39a17b08da618b5ed84169ec4b5744039..367511bfb78142920ce0ee5606636327fb186d76 100644
--- a/indra/cmake/BuildPackagesInfo.cmake
+++ b/indra/cmake/BuildPackagesInfo.cmake
@@ -2,9 +2,16 @@
 # Construct the version and copyright information based on package data.
 include(Python)
 
+# packages-formatter.py runs autobuild install --versions, which needs to know
+# the build_directory, which (on Windows) depends on AUTOBUILD_ADDRSIZE.
+# Within an autobuild build, AUTOBUILD_ADDRSIZE is already set. But when
+# building in an IDE, it probably isn't. Set it explicitly using
+# run_build_test.py.
 add_custom_command(OUTPUT packages-info.txt
   COMMENT Generating packages-info.txt for the about box
   MAIN_DEPENDENCY ${CMAKE_SOURCE_DIR}/../autobuild.xml
   DEPENDS ${CMAKE_SOURCE_DIR}/../scripts/packages-formatter.py
-  COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_SOURCE_DIR}/../scripts/packages-formatter.py > packages-info.txt
+  COMMAND ${PYTHON_EXECUTABLE}
+          ${CMAKE_SOURCE_DIR}/cmake/run_build_test.py -DAUTOBUILD_ADDRSIZE=${ADDRESS_SIZE}
+          ${CMAKE_SOURCE_DIR}/../scripts/packages-formatter.py > packages-info.txt
   )