diff --git a/bignum.c b/bignum.c
index 4b01316d22..e04843f478 100644
--- a/bignum.c
+++ b/bignum.c
@@ -30,9 +30,6 @@
 # define USE_GMP 0
 #endif
 #endif
-#if USE_GMP
-# include <gmp.h>
-#endif
 
 #include "id.h"
 #include "internal.h"
@@ -48,6 +45,15 @@
 #include "ruby/util.h"
 #include "ruby_assert.h"
 
+#if USE_GMP
+RBIMPL_WARNING_PUSH()
+# ifdef _MSC_VER
+RBIMPL_WARNING_IGNORED(4146) /* for mpn_neg() */
+# endif
+# include <gmp.h>
+RBIMPL_WARNING_POP()
+#endif
+
 static const bool debug_integer_pack = (
 #ifdef DEBUG_INTEGER_PACK
     DEBUG_INTEGER_PACK+0
diff --git a/rational.c b/rational.c
index 014cbb6c6a..1b162e7b56 100644
--- a/rational.c
+++ b/rational.c
@@ -22,9 +22,6 @@
 # define USE_GMP 0
 #endif
 #endif
-#if USE_GMP
-#include <gmp.h>
-#endif
 
 #include "id.h"
 #include "internal.h"
@@ -36,6 +33,15 @@
 #include "internal/rational.h"
 #include "ruby_assert.h"
 
+#if USE_GMP
+RBIMPL_WARNING_PUSH()
+# ifdef _MSC_VER
+RBIMPL_WARNING_IGNORED(4146) /* for mpn_neg() */
+# endif
+# include <gmp.h>
+RBIMPL_WARNING_POP()
+#endif
+
 #define ZERO INT2FIX(0)
 #define ONE INT2FIX(1)
 #define TWO INT2FIX(2)