diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index e153047b778..02f5d12db1a 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -115,6 +115,7 @@ Copyright (C) 1994 Steen Lumholt.
 #ifdef MS_WINDOWS
 #include <conio.h>
 #define WAIT_FOR_STDIN
+#endif
 
 static PyObject *
 _get_tcl_lib_path()
@@ -132,6 +133,7 @@ _get_tcl_lib_path()
             return NULL;
         }
 
+#ifdef MS_WINDOWS
         /* Check expected location for an installed Python first */
         tcl_library_path = PyUnicode_FromString("\\tcl\\tcl" TCL_VERSION);
         if (tcl_library_path == NULL) {
@@ -169,11 +171,31 @@ _get_tcl_lib_path()
             tcl_library_path = NULL;
 #endif
         }
+#else
+        /* Check expected location for an installed Python first */
+        tcl_library_path = PyUnicode_FromString("/lib/tcl" TCL_VERSION);
+        if (tcl_library_path == NULL) {
+            return NULL;
+        }
+        tcl_library_path = PyUnicode_Concat(prefix, tcl_library_path);
+        if (tcl_library_path == NULL) {
+            return NULL;
+        }
+        stat_return_value = _Py_stat(tcl_library_path, &stat_buf);
+        if (stat_return_value == -2) {
+            return NULL;
+        }
+        if (stat_return_value == -1) {
+            /* install location doesn't exist, reset errno and leave Tcl
+               to its own devices */
+            errno = 0;
+            tcl_library_path = NULL;
+        }
+#endif
         already_checked = 1;
     }
     return tcl_library_path;
 }
-#endif /* MS_WINDOWS */
 
 /* The threading situation is complicated.  Tcl is not thread-safe, except
    when configured with --enable-threads.
@@ -822,6 +844,30 @@ Tkapp_New(const char *screenName, const char *className,
 
         ret = GetEnvironmentVariableW(L"TCL_LIBRARY", NULL, 0);
         if (!ret && GetLastError() == ERROR_ENVVAR_NOT_FOUND) {
+            str_path = _get_tcl_lib_path();
+            if (str_path == NULL && PyErr_Occurred()) {
+                return NULL;
+            }
+            if (str_path != NULL) {
+                utf8_path = PyUnicode_AsUTF8String(str_path);
+                if (utf8_path == NULL) {
+                    return NULL;
+                }
+                Tcl_SetVar(v->interp,
+                           "tcl_library",
+                           PyBytes_AS_STRING(utf8_path),
+                           TCL_GLOBAL_ONLY);
+                Py_DECREF(utf8_path);
+            }
+        }
+    }
+#else
+    {
+        const char *env_val = getenv("TCL_LIBRARY");
+        if (!env_val) {
+            PyObject *str_path;
+            PyObject *utf8_path;
+
             str_path = _get_tcl_lib_path();
             if (str_path == NULL && PyErr_Occurred()) {
                 return NULL;
@@ -3631,7 +3677,32 @@ PyInit__tkinter(void)
                 PyMem_Free(wcs_path);
             }
 #else
+            int set_var = 0;
+            PyObject *str_path;
+            char *path;
+
+            if (!getenv("TCL_LIBRARY")) {
+                str_path = _get_tcl_lib_path();
+                if (str_path == NULL && PyErr_Occurred()) {
+                    Py_DECREF(m);
+                    return NULL;
+                }
+                if (str_path != NULL) {
+                    path = PyUnicode_AsUTF8(str_path);
+                    if (path == NULL) {
+                        Py_DECREF(m);
+                        return NULL;
+                    }
+                    setenv("TCL_LIBRARY", path, 1);
+                    set_var = 1;
+                }
+            }
+
             Tcl_FindExecutable(PyBytes_AS_STRING(cexe));
+
+            if (set_var) {
+                unsetenv("TCL_LIBRARY");
+            }
 #endif /* MS_WINDOWS */
         }
         Py_XDECREF(cexe);