diff --git a/bignum.c b/bignum.c
index 9e73927e69..f806558b97 100644
--- a/bignum.c
+++ b/bignum.c
@@ -3144,7 +3144,7 @@ rb_big_norm(VALUE x)
 }
 
 VALUE
-rb_uint2big(VALUE n)
+rb_uint2big(uintptr_t n)
 {
     long i;
     VALUE big = bignew(bdigit_roomof(SIZEOF_VALUE), 1);
@@ -3166,7 +3166,7 @@ rb_uint2big(VALUE n)
 }
 
 VALUE
-rb_int2big(SIGNED_VALUE n)
+rb_int2big(intptr_t n)
 {
     long neg = 0;
     VALUE u;
@@ -3187,14 +3187,14 @@ rb_int2big(SIGNED_VALUE n)
 }
 
 VALUE
-rb_uint2inum(VALUE n)
+rb_uint2inum(uintptr_t n)
 {
     if (POSFIXABLE(n)) return LONG2FIX(n);
     return rb_uint2big(n);
 }
 
 VALUE
-rb_int2inum(SIGNED_VALUE n)
+rb_int2inum(intptr_t n)
 {
     if (FIXABLE(n)) return LONG2FIX(n);
     return rb_int2big(n);
@@ -5933,7 +5933,7 @@ bigdivrem(VALUE x, VALUE y, volatile VALUE *divp, volatile VALUE *modp)
 	zds = BDIGITS(z);
         dd = bigdivrem_single(zds, xds, xn, dd);
 	if (modp) {
-	    *modp = rb_uint2big((VALUE)dd);
+	    *modp = rb_uint2big((uintptr_t)dd);
 	    BIGNUM_SET_SIGN(*modp, BIGNUM_SIGN(x));
 	}
 	if (divp) *divp = z;
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 6578ffe66d..74c87e9709 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -747,8 +747,8 @@ rb_num2ll_inline(VALUE x)
 double rb_num2dbl(VALUE);
 #define NUM2DBL(x) rb_num2dbl((VALUE)(x))
 
-VALUE rb_uint2big(VALUE);
-VALUE rb_int2big(SIGNED_VALUE);
+VALUE rb_uint2big(uintptr_t);
+VALUE rb_int2big(intptr_t);
 
 VALUE rb_newobj(void);
 VALUE rb_newobj_of(VALUE, VALUE);