diff --git a/win32_build.sh b/win32_build.sh
index 0b00ee46525..3a11b942dec 100755
--- a/win32_build.sh
+++ b/win32_build.sh
@@ -20,7 +20,9 @@ SKIP_CMAKE=${SKIP_CMAKE:-}
 SKIP_DLL_COPY=${SKIP_DLL_COPY:-}
 SKIP_TESTS=${SKIP_TESTS:-}
 SKIP_BINDIR_CLEAN=${SKIP_BINDIR_CLEAN:-}
-NUM_WORKERS=${NUM_WORKERS:-$num_vcpus}
+# Use Ninja's default, it might be useful when having few cores.
+NUM_WORKERS_DEFAULT=$(( $num_vcpus + 2 ))
+NUM_WORKERS=${NUM_WORKERS:-$NUM_WORKERS_DEFAULT}
 DEV_BUILD=${DEV_BUILD:-}
 # Unless SKIP_ZIP is set, we're preparing an archive that contains the Ceph
 # binaries, debug symbols as well as the required DLLs.
@@ -77,7 +79,7 @@ dbgSymbolDir="$strippedBinDir/${dbgDirname}"
 depsSrcDir="$DEPS_DIR/src"
 depsToolsetDir="$DEPS_DIR/mingw"
 
-generatorUsed="Unix Makefiles"
+cmakeGenerator="Ninja"
 lz4Dir="${depsToolsetDir}/lz4"
 sslDir="${depsToolsetDir}/openssl"
 curlDir="${depsToolsetDir}/curl"
@@ -168,7 +170,7 @@ cmake -D CMAKE_PREFIX_PATH=$depsDirs \
       -D WITH_CEPH_DEBUG_MUTEX=$WITH_CEPH_DEBUG_MUTEX \
       -D DOKAN_INCLUDE_DIRS="$dokanSrcDir/dokan" \
       -D DOKAN_LIBRARIES="$dokanLibDir/libdokan.a" \
-      -G "$generatorUsed" \
+      -G "$cmakeGenerator" \
       $CEPH_DIR  2>&1 | tee "${BUILD_DIR}/cmake.log"
 fi # [[ -z $SKIP_CMAKE ]]
 
@@ -176,26 +178,17 @@ if [[ -z $SKIP_BUILD ]]; then
     echo "Building using $NUM_WORKERS workers. Log: ${BUILD_DIR}/build.log"
     echo "" > "${BUILD_DIR}/build.log"
 
-    # We're going to use an associative array having subdirectories as keys
-    # and targets as values.
-    declare -A make_targets
-    make_targets["src/tools"]="ceph-conf rados"
-    make_targets["src/tools/immutable_object_cache"]="all"
-    make_targets["src/tools/rbd"]="all"
-    make_targets["src/tools/rbd_wnbd"]="all"
-    make_targets["src/compressor"]="all"
-    make_targets["src"]="cephfs"
-    make_targets["src/dokan"]="all"
-
+    cd $BUILD_DIR
+    ninja_targets="rados rbd rbd-wnbd "
+    ninja_targets+=" ceph-conf ceph-immutable-object-cache"
+    ninja_targets+=" cephfs ceph-dokan"
+    # TODO: do we actually need the ceph compression libs?
+    ninja_targets+=" compressor ceph_lz4 ceph_snappy ceph_zlib ceph_zstd"
     if [[ -z $SKIP_TESTS ]]; then
-      make_targets["src/tools"]+=" ceph_radosacl ceph_scratchtool"
-      make_targets["src/test"]="all"
+      ninja_targets+=" test ceph_radosacl ceph_scratchtool"
     fi
 
-    for target_subdir in "${!make_targets[@]}"; do
-      echo "Building $target_subdir: ${make_targets[$target_subdir]}" | tee -a "${BUILD_DIR}/build.log"
-      make -j $NUM_WORKERS -C $target_subdir ${make_targets[$target_subdir]} 2>&1 | tee -a "${BUILD_DIR}/build.log"
-    done
+    ninja -v $ninja_targets 2>&1 | tee "${BUILD_DIR}/build.log"
 fi
 
 if [[ -z $SKIP_DLL_COPY ]]; then