diff --git a/appveyor.yml b/appveyor.yml
index 551a7b44e..877f841f1 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -279,8 +279,8 @@
       C:\cygwin64\bin\bash --login -c "
         set -e;
         cd build/cmake;
-        CFLAGS='-O1 -Werror' cmake -G 'Unix Makefiles' -DCMAKE_BUILD_TYPE=Debug -DZSTD_BUILD_TESTS:BOOL=ON -DZSTD_FUZZER_FLAGS=-T20s -DZSTD_ZSTREAM_FLAGS=-T20s -DZSTD_FULLBENCH_FLAGS=-i0 .;
-        make VERBOSE=1 -j4;
+        CC=clang CFLAGS='-O1 -Werror' cmake -G 'Unix Makefiles' -DCMAKE_BUILD_TYPE=Debug -DZSTD_BUILD_TESTS:BOOL=ON -DZSTD_FUZZER_FLAGS=-T20s -DZSTD_ZSTREAM_FLAGS=-T20s -DZSTD_FULLBENCH_FLAGS=-i0 .;
+        make VERBOSE=1 -j;
         ctest -V -L Medium;
       "
     )