Index: appveyor.yml
===================================================================
diff -u -r0c1811dc321a2bfaf252b2e68326d93bc014fa27 -r00eb377bbd5cf0e6579ac92de033e0e6b9ea77f5
--- appveyor.yml	(.../appveyor.yml)	(revision 0c1811dc321a2bfaf252b2e68326d93bc014fa27)
+++ appveyor.yml	(.../appveyor.yml)	(revision 00eb377bbd5cf0e6579ac92de033e0e6b9ea77f5)
@@ -23,7 +23,7 @@
   # - set PATH=%CD%\%MINGW_DIR%\bin;C:\msys64\usr\bin;%PATH%
   - set PATH=C:\msys64\mingw64\bin;C:\msys64\usr\bin;%PATH%
   - set PATH
-  - bash -lc "echo \"export PATH=/c/msys64/mingw64/bin:\$PATH; export MSYSTEM=MINGW64;\" >> ~/.bash_profile"
+  - bash -lc "echo \"export PATH=/c/msys64/mingw64/bin:\$PATH; export MSYSTEM=MINGW64; export MINGW_PREFIX=/c/msys64/mingw64; \" >> ~/.bash_profile"
   - bash -lc "echo \$PATH"
 
 build_script: