diff --git a/src/os_win32.c b/src/os_win32.c
index 330ce5a..a2b2c50 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -548,6 +548,8 @@
 #ifdef _MSC_VER
 // The ToAscii bug destroys several registers.	Need to turn off optimization
 // or the GetConsoleKeyboardLayoutName hack will fail in non-debug versions
+# pragma warning(push)
+# pragma warning(disable: 4748)
 # pragma optimize("", off)
 #endif
 
@@ -619,6 +621,7 @@
 /* MUST switch optimization on again here, otherwise a call to
  * decode_key_event() may crash (e.g. when hitting caps-lock) */
 # pragma optimize("", on)
+# pragma warning(pop)
 
 # if (_MSC_VER < 1100)
 /* MUST turn off global optimisation for this next function, or