diff --git a/.appveyor.yml b/.appveyor.yml
index 660b0aac9..482890543 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -1,14 +1,10 @@
 version: '{build}'
 
-#cache:
-#- x86_64-4.9.2-release-win32-seh-rt_v4-rev4.7z -> .appveyor.yml
-#- i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z -> .appveyor.yml
-
-# https://www.appveyor.com/docs/windows-images-software/#mingw-msys-cygwin
+# use an image with recent Mingw-w64 versions available on both architectures: https://www.appveyor.com/docs/windows-images-software/#mingw-msys-cygwin
 image: Visual Studio 2015
 
 matrix:
-  # We always want 32 and 64-bit compilation
+  # We always want 32-bit and 64-bit compilation
   fast_finish: false
 
 platform:
@@ -19,28 +15,7 @@ platform:
 clone_depth: 10
 
 install:
-  #- setlocal EnableExtensions EnableDelayedExpansion
-
-  #- IF "%PLATFORM%" == "x86" (
-      #SET "MINGW_ARCHIVE=i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z" &
-      #SET "MINGW_URL=https://sourceforge.net/projects/mingw-w64/files/Toolchains%%20targetting%%20Win32/Personal%%20Builds/mingw-builds/4.9.2/threads-win32/dwarf/i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z" &
-      #SET "MINGW_DIR=mingw32"
-    #) ELSE (
-      #IF "%PLATFORM%" == "x64" (
-        #SET "MINGW_ARCHIVE=x86_64-4.9.2-release-win32-seh-rt_v4-rev4.7z" &
-        #SET "MINGW_URL=https://sourceforge.net/projects/mingw-w64/files/Toolchains%%20targetting%%20Win64/Personal%%20Builds/mingw-builds/4.9.2/threads-win32/seh/x86_64-4.9.2-release-win32-seh-rt_v4-rev4.7z" &
-        #SET "MINGW_DIR=mingw64"
-      #) else (
-        #echo "Unknown platform"
-      #)
-    #)
-
-  #- SET "PATH=%CD%\%MINGW_DIR%\bin;%PATH%"
-
-  ## download and unpack Mingw-w64
-  #- IF NOT EXIST "%MINGW_ARCHIVE%" appveyor DownloadFile "%MINGW_URL%" -FileName "%MINGW_ARCHIVE%"
-  #- 7z x -y "%MINGW_ARCHIVE%" > nul
-
+  # use the newest versions documented here: https://www.appveyor.com/docs/windows-images-software/#mingw-msys-cygwin
   - IF "%PLATFORM%" == "x86" SET PATH=C:\mingw-w64\i686-6.3.0-posix-dwarf-rt_v5-rev1\mingw32\bin;%PATH%
   - IF "%PLATFORM%" == "x64" SET PATH=C:\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\bin;%PATH%
 
@@ -48,6 +23,7 @@ build_script:
   - cd C:\projects\%APPVEYOR_PROJECT_SLUG%
   # speed up submodule cloning
   - git submodule update --init --recursive --depth 10
+  # the 32-bit build is done on a 64-bit image, so we need to override the architecture
   - mingw32-make ARCH_OVERRIDE=%PLATFORM% fetch-dlls
   - mingw32-make -j2 ARCH_OVERRIDE=%PLATFORM% nimbus