diff --git a/unix/tclUnixInit.c b/unix/tclUnixInit.c
index 746793815b70..47b8df361a8b 100644
--- a/unix/tclUnixInit.c
+++ b/unix/tclUnixInit.c
@@ -895,6 +895,9 @@ TclpSetVariables(
 
     GetSystemInfo(&sysInfo);
 
+    if (osInfo.dwMajorVersion == 10 && osInfo.dwBuildNumber >= 22000) {
+	osInfo.dwMajorVersion = 11;
+    }
     Tcl_SetVar2(interp, "tcl_platform", "os", "Windows NT", TCL_GLOBAL_ONLY);
     sprintf(buffer, "%d.%d", osInfo.dwMajorVersion, osInfo.dwMinorVersion);
     Tcl_SetVar2(interp, "tcl_platform", "osVersion", buffer, TCL_GLOBAL_ONLY);
diff --git a/win/tclWinInit.c b/win/tclWinInit.c
index eae44044faae..582c7000df24 100644
--- a/win/tclWinInit.c
+++ b/win/tclWinInit.c
@@ -552,6 +552,9 @@ TclpSetVariables(
 	    TCL_GLOBAL_ONLY);
     Tcl_SetVar2(interp, "tcl_platform", "os",
 	    "Windows NT", TCL_GLOBAL_ONLY);
+    if (osInfo.dwMajorVersion == 10 && osInfo.dwBuildNumber >= 22000) {
+	osInfo.dwMajorVersion = 11;
+    }
     wsprintfA(buffer, "%d.%d", osInfo.dwMajorVersion, osInfo.dwMinorVersion);
     Tcl_SetVar2(interp, "tcl_platform", "osVersion", buffer, TCL_GLOBAL_ONLY);
     if (sys.oemId.wProcessorArchitecture < NUMPROCESSORS) {