diff --git a/configure.ac b/configure.ac
index 5232c8f..9a489d9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -166,13 +166,18 @@
   CPPFLAGS="$CPPFLAGS -I${srcdir}/include/msvc_compat/C99"
 fi
 
-AC_CHECK_SIZEOF([void *])
-if test "x${ac_cv_sizeof_void_p}" = "x8" ; then
-  LG_SIZEOF_PTR=3
-elif test "x${ac_cv_sizeof_void_p}" = "x4" ; then
-  LG_SIZEOF_PTR=2
+if test "x${je_cv_msvc}" = "xyes" ; then
+  LG_SIZEOF_PTR=LG_SIZEOF_PTR_WIN
+  AC_MSG_RESULT([Using a predefined value for sizeof(void *): 4 for 32-bit, 8 for 64-bit])
 else
-  AC_MSG_ERROR([Unsupported pointer size: ${ac_cv_sizeof_void_p}])
+  AC_CHECK_SIZEOF([void *])
+  if test "x${ac_cv_sizeof_void_p}" = "x8" ; then
+    LG_SIZEOF_PTR=3
+  elif test "x${ac_cv_sizeof_void_p}" = "x4" ; then
+    LG_SIZEOF_PTR=2
+  else
+    AC_MSG_ERROR([Unsupported pointer size: ${ac_cv_sizeof_void_p}])
+  fi
 fi
 AC_DEFINE_UNQUOTED([LG_SIZEOF_PTR], [$LG_SIZEOF_PTR])