diff --git a/arb.h b/arb.h
index bcee4bdc..9e88609e 100644
--- a/arb.h
+++ b/arb.h
@@ -294,8 +294,8 @@ arb_get_rad_arb(arb_t z, const arb_t x)
 
 void arb_get_abs_ubound_arf(arf_t u, const arb_t x, slong prec);
 void arb_get_abs_lbound_arf(arf_t u, const arb_t x, slong prec);
-void arb_get_ubound_arf(arf_t u, const arb_t x, long prec);
-void arb_get_lbound_arf(arf_t u, const arb_t x, long prec);
+void arb_get_ubound_arf(arf_t u, const arb_t x, slong prec);
+void arb_get_lbound_arf(arf_t u, const arb_t x, slong prec);
 
 void arb_nonnegative_part(arb_t res, const arb_t x);
 
diff --git a/arb/get_lbound_arf.c b/arb/get_lbound_arf.c
index e7a99350..d2990750 100644
--- a/arb/get_lbound_arf.c
+++ b/arb/get_lbound_arf.c
@@ -12,7 +12,7 @@
 #include "arb.h"
 
 void
-arb_get_lbound_arf(arf_t u, const arb_t x, long prec)
+arb_get_lbound_arf(arf_t u, const arb_t x, slong prec)
 {
     arf_t t;
     arf_init_set_mag_shallow(t, arb_radref(x));
diff --git a/arb/get_ubound_arf.c b/arb/get_ubound_arf.c
index 3245dc7b..eac4ee93 100644
--- a/arb/get_ubound_arf.c
+++ b/arb/get_ubound_arf.c
@@ -12,7 +12,7 @@
 #include "arb.h"
 
 void
-arb_get_ubound_arf(arf_t u, const arb_t x, long prec)
+arb_get_ubound_arf(arf_t u, const arb_t x, slong prec)
 {
     arf_t t;
     arf_init_set_mag_shallow(t, arb_radref(x));
diff --git a/doc/source/arb.rst b/doc/source/arb.rst
index 47c3d5d5..aa0f5869 100644
--- a/doc/source/arb.rst
+++ b/doc/source/arb.rst
@@ -419,12 +419,12 @@ Radius and interval operations
     Sets *u* to the lower bound for the absolute value of *x*,
     rounded down to *prec* bits. If *x* contains NaN, the result is NaN.
 
-.. function:: void arb_get_ubound_arf(arf_t u, const arb_t x, long prec)
+.. function:: void arb_get_ubound_arf(arf_t u, const arb_t x, slong prec)
 
     Sets *u* to the upper bound for the value of *x*,
     rounded up to *prec* bits. If *x* contains NaN, the result is NaN.
 
-.. function:: void arb_get_lbound_arf(arf_t u, const arb_t x, long prec)
+.. function:: void arb_get_lbound_arf(arf_t u, const arb_t x, slong prec)
 
     Sets *u* to the lower bound for the value of *x*,
     rounded down to *prec* bits. If *x* contains NaN, the result is NaN.