diff --git a/.appveyor.yml b/.appveyor.yml
index 9487c75..1408fb4 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -1,37 +1,40 @@
 version: '{build}'
 
 cache:
+- nim-0.18.0_x64.zip
 - x86_64-4.9.2-release-win32-seh-rt_v4-rev4.7z
-- i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z
+- packages -> **\packages.config
+- '%LocalAppData%\NuGet\Cache -> **\packages.config'
 
 matrix:
   fast_finish: true
 
 environment:
   matrix:
-    - MINGW_DIR: mingw64
-      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/download
-      MINGW_ARCHIVE: x86_64-4.9.2-release-win32-seh-rt_v4-rev4.7z
+    - MINGW_ARCHIVE: x86_64-4.9.2-release-win32-seh-rt_v4-rev4.7z
+      MINGW_DIR: mingw64
+      # We need to hardcode a mirror otherwise the download fails
+      MINGW_URL: https://ayera.dl.sourceforge.net/project/mingw-w64/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
+      NIM_ARCHIVE: nim-0.18.0_x64.zip
+      NIM_DIR: nim-0.18.0
+      NIM_URL: https://nim-lang.org/download/nim-0.18.0_x64.zip
       platform: x64
-    - MINGW_DIR: mingw32
-      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/download
-      MINGW_ARCHIVE: i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z
+    - MINGW_ARCHIVE: i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z
+      MINGW_DIR: mingw64
+      # We need to hardcode a mirror otherwise the download fails
+      MINGW_URL: https://ayera.dl.sourceforge.net/project/mingw-w64/Toolchains%20targetting%20Win64/Personal%20Builds/mingw-builds/4.9.2/threads-win32/seh/i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z
+      NIM_ARCHIVE: nim-0.18.0_x64.zip
+      NIM_DIR: nim-0.18.0
+      NIM_URL: https://nim-lang.org/download/nim-0.18.0_x32.zip
       platform: x86
 
 install:
+  - MKDIR %CD%\tools_tmp
   - IF not exist "%MINGW_ARCHIVE%" appveyor DownloadFile "%MINGW_URL%" -FileName "%MINGW_ARCHIVE%"
-  - 7z x -y "%MINGW_ARCHIVE%" > nul
-  - SET PATH=%CD%\%MINGW_DIR%\bin;%CD%\Nim\bin;%PATH%
-  - git clone https://github.com/nim-lang/Nim.git %CD%\Nim
-  - cd %CD%\Nim
-  - git clone --depth 1 https://github.com/nim-lang/csources
-  - cd csources
-  - IF "%PLATFORM%" == "x64" ( build64.bat ) else ( build.bat )
-  - cd ..
-  - bin\nim.exe c koch
-  - koch.exe boot -d:release
-  - koch.exe nimble
-  - cd %CD%
+  - 7z x -y "%MINGW_ARCHIVE%" -o"%CD%\tools_tmp"> nul
+  - IF not exist "%NIM_ARCHIVE%" appveyor DownloadFile "%NIM_URL%" -FileName "%NIM_ARCHIVE%"
+  - 7z x -y "%NIM_ARCHIVE%" -o"%CD%\tools_tmp"> nul
+  - SET PATH=%CD%\tools_tmp\%NIM_DIR%\bin;%CD%\tools_tmp\%MINGW_DIR%\bin;%PATH%
   - SET PATH=%PATH%;%CD%
 
 build_script:
diff --git a/secp256k1.nimble b/secp256k1.nimble
index 66d5a68..2fca35e 100644
--- a/secp256k1.nimble
+++ b/secp256k1.nimble
@@ -7,17 +7,4 @@ description   = "A wrapper for the libsecp256k1 C library"
 license       = "Apache License 2.0"
 skipDirs      = @["tests"]
 
-requires "nim >= 0.17.0"
-
-proc test(name: string, lang: string = "c") =
-  if not dirExists "build":
-    mkDir "build"
-  if not dirExists "nimcache":
-    mkDir "nimcache"
-  --run
-  --nimcache: "nimcache"
-  switch("out", ("./build/" & name))
-  setCommand lang, "tests/" & name & ".nim"
-
-task test, "Run Proof-of-Work tests (without mining)":
-  test "test1"
+requires "nim >= 0.18.0"