diff --git a/scripts/mk_unix_dist.py b/scripts/mk_unix_dist.py
index 72a7ba15f..d152b3625 100644
--- a/scripts/mk_unix_dist.py
+++ b/scripts/mk_unix_dist.py
@@ -28,7 +28,7 @@ JAVA_ENABLED=True
 GIT_HASH=False
 PYTHON_ENABLED=True
 MAKEJOBS=getenv("MAKEJOBS", '8')
-OS_VERSION=None
+OS_NAME=None
 
 def set_verbose(flag):
     global VERBOSE
@@ -66,7 +66,7 @@ def display_help():
 
 # Parse configuration option for mk_make script
 def parse_options():
-    global FORCE_MK, JAVA_ENABLED, GIT_HASH, DOTNET_CORE_ENABLED, DOTNET_KEY_FILE, OS_VERSION
+    global FORCE_MK, JAVA_ENABLED, GIT_HASH, DOTNET_CORE_ENABLED, DOTNET_KEY_FILE, OS_NAME
     path = BUILD_DIR
     options, remainder = getopt.gnu_getopt(sys.argv[1:], 'b:hsf', ['build=',
                                                                    'help',
@@ -107,7 +107,7 @@ def parse_options():
             else:
                 raise MKException("Invalid architecture directive '%s'. Legal directives: arm64" % arg)
         elif opt == '--os':
-            OS_VERSION = arg
+            OS_NAME = arg
         else:
             raise MKException("Invalid command line option '%s'" % opt)
     set_build_dir(path)
@@ -159,8 +159,8 @@ def mk_z3():
             return 1
 
 def get_os_name():
-    if OS_VERSION is not None:
-        return OS_VERSION
+    if OS_NAME is not None:
+        return OS_NAME
     import platform
     basic = os.uname()[0].lower()
     if basic == 'linux':
diff --git a/scripts/nightly.yaml b/scripts/nightly.yaml
index b20db08b6..6a91310ff 100644
--- a/scripts/nightly.yaml
+++ b/scripts/nightly.yaml
@@ -29,7 +29,7 @@ stages:
     pool:
       vmImage: "macOS-12"
     steps:
-    - script: python scripts/mk_unix_dist.py --dotnet-key=$(Build.SourcesDirectory)/resources/z3.snk --arch=arm64 --nojava --os=11.0
+    - script: python scripts/mk_unix_dist.py --dotnet-key=$(Build.SourcesDirectory)/resources/z3.snk --arch=arm64 --nojava --os=osx-11.0
     - script: git clone https://github.com/z3prover/z3test z3test
     - script: cp dist/*.zip $(Build.ArtifactStagingDirectory)/.
     - task: PublishPipelineArtifact@1