diff --git a/target/arm/arm-semi.c b/target/arm/arm-semi.c
index 958083a105..ecd51338fd 100644
--- a/target/arm/arm-semi.c
+++ b/target/arm/arm-semi.c
@@ -388,6 +388,7 @@ typedef uint32_t sys_writefn(ARMCPU *cpu, GuestFD *gf,
                              target_ulong buf, uint32_t len);
 typedef uint32_t sys_readfn(ARMCPU *cpu, GuestFD *gf,
                             target_ulong buf, uint32_t len);
+typedef uint32_t sys_isattyfn(ARMCPU *cpu, GuestFD *gf);
 
 static uint32_t host_closefn(ARMCPU *cpu, GuestFD *gf)
 {
@@ -436,6 +437,11 @@ static uint32_t host_readfn(ARMCPU *cpu, GuestFD *gf,
     return len - ret;
 }
 
+static uint32_t host_isattyfn(ARMCPU *cpu, GuestFD *gf)
+{
+    return isatty(gf->hostfd);
+}
+
 static uint32_t gdb_closefn(ARMCPU *cpu, GuestFD *gf)
 {
     return arm_gdb_syscall(cpu, arm_semi_cb, "close,%x", gf->hostfd);
@@ -457,10 +463,16 @@ static uint32_t gdb_readfn(ARMCPU *cpu, GuestFD *gf,
                            gf->hostfd, buf, len);
 }
 
+static uint32_t gdb_isattyfn(ARMCPU *cpu, GuestFD *gf)
+{
+    return arm_gdb_syscall(cpu, arm_semi_cb, "isatty,%x", gf->hostfd);
+}
+
 typedef struct GuestFDFunctions {
     sys_closefn *closefn;
     sys_writefn *writefn;
     sys_readfn *readfn;
+    sys_isattyfn *isattyfn;
 } GuestFDFunctions;
 
 static const GuestFDFunctions guestfd_fns[] = {
@@ -468,11 +480,13 @@ static const GuestFDFunctions guestfd_fns[] = {
         .closefn = host_closefn,
         .writefn = host_writefn,
         .readfn = host_readfn,
+        .isattyfn = host_isattyfn,
     },
     [GuestFDGDB] = {
         .closefn = gdb_closefn,
         .writefn = gdb_writefn,
         .readfn = gdb_readfn,
+        .isattyfn = gdb_isattyfn,
     },
 };
 
@@ -631,11 +645,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
             return set_swi_errno(env, -1);
         }
 
-        if (use_gdb_syscalls()) {
-            return arm_gdb_syscall(cpu, arm_semi_cb, "isatty,%x", gf->hostfd);
-        } else {
-            return isatty(gf->hostfd);
-        }
+        return guestfd_fns[gf->type].isattyfn(cpu, gf);
     case TARGET_SYS_SEEK:
         GET_ARG(0);
         GET_ARG(1);