diff --git a/dlls/setupapi/install.c b/dlls/setupapi/install.c
index 435918e815e..8a28bfcc4e1 100644
--- a/dlls/setupapi/install.c
+++ b/dlls/setupapi/install.c
@@ -233,8 +233,27 @@ static bool append_multi_sz_value( HKEY hkey, const WCHAR *value, const WCHAR *s
 {
     DWORD size, type, total;
     WCHAR *buffer, *p;
+    LONG ret;
+
+    if ((ret = RegQueryValueExW( hkey, value, NULL, &type, NULL, &size )))
+    {
+        if (ret != ERROR_FILE_NOT_FOUND)
+        {
+            ERR( "failed to query value %s, error %lu\n", debugstr_w(value), ret );
+            SetLastError( ret );
+            return false;
+        }
+
+        if ((ret = RegSetValueExW( hkey, value, 0, REG_MULTI_SZ, (BYTE *)strings, str_size * sizeof(WCHAR) )))
+        {
+            ERR( "failed to set value %s, error %lu\n", debugstr_w(value), ret );
+            SetLastError( ret );
+            return false;
+        }
+
+        return true;
+    }
 
-    if (RegQueryValueExW( hkey, value, NULL, &type, NULL, &size )) return true;
     if (type != REG_MULTI_SZ)
     {
         WARN( "value %s exists but has wrong type %#lx\n", debugstr_w(value), type );
diff --git a/dlls/setupapi/tests/install.c b/dlls/setupapi/tests/install.c
index 10c93482ece..318f1294210 100644
--- a/dlls/setupapi/tests/install.c
+++ b/dlls/setupapi/tests/install.c
@@ -2332,13 +2332,10 @@ static void test_append_reg(void)
     ok(!l, "Got error %lu.\n", l);
     size = sizeof(value);
     l = RegQueryValueExA(key, "value", NULL, &type, (BYTE *)value, &size);
-    todo_wine ok(!l, "Got error %lu.\n", l);
-    if (!l)
-    {
-        ok(type == REG_MULTI_SZ, "Got type %#lx.\n", type);
-        ok(size == sizeof("data\0"), "Got size %lu.\n", size);
-        ok(!memcmp(value, "data\0", size), "Got data %s.\n", debugstr_an(value, size));
-    }
+    ok(!l, "Got error %lu.\n", l);
+    ok(type == REG_MULTI_SZ, "Got type %#lx.\n", type);
+    ok(size == sizeof("data\0"), "Got size %lu.\n", size);
+    ok(!memcmp(value, "data\0", size), "Got data %s.\n", debugstr_an(value, size));
 
     /* Key exists and already has a value. */