diff -Naur Python-3.7.0-orig/Modules/getpath.c Python-3.7.0/Modules/getpath.c
--- Python-3.7.0-orig/Modules/getpath.c	2018-07-12 10:21:50.372404600 +0300
+++ Python-3.7.0/Modules/getpath.c	2018-07-12 10:21:50.700005100 +0300
@@ -1005,6 +1005,31 @@
     memset(exec_prefix, 0, sizeof(exec_prefix));
     calculate_exec_prefix(core_config, calculate, exec_prefix);
 
+#ifdef MS_WINDOWS
+    if (calculate->path_env) {
+        wchar_t *module_path, *new_path;
+        // Add path of executable/dll to system path. This
+        // is so that the correct tcl??.dll and tk??.dll get used.
+        module_path = config->dll_path[0] ? config->dll_path : config->program_full_path;
+        new_path = (wchar_t *)alloca(sizeof(wchar_t)*(wcslen(L"PATH=") + wcslen(module_path) + 1 + wcslen(calculate->path_env) + 1));
+        if (new_path) {
+            wchar_t *slashes, *end;
+            wcscpy(new_path, L"PATH=");
+            wcscat(new_path, module_path);
+            slashes = wcschr(new_path, L'/');
+            while (slashes) {
+                *slashes = L'\\';
+                slashes = wcschr(slashes+1, L'/');
+            }
+            end = wcsrchr(new_path, L'\\') ? wcsrchr(new_path, L'\\') : new_path + wcslen(new_path);
+            end[0] = L';';
+            end[1] = L'\0';
+            wcscat(new_path, calculate->path_env);
+            _wputenv(new_path);
+        }
+    }
+#endif
+
     if ((!calculate->prefix_found || !calculate->exec_prefix_found) &&
         !Py_FrozenFlag)
     {