diff --git a/linux-user/cris/signal.c b/linux-user/cris/signal.c
index 0b405247cf..1e02194377 100644
--- a/linux-user/cris/signal.c
+++ b/linux-user/cris/signal.c
@@ -146,7 +146,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
                     target_siginfo_t *info,
                      target_sigset_t *set, CPUCRISState *env)
 {
-    fprintf(stderr, "CRIS setup_rt_frame: not implemented\n");
+    qemu_log_mask(LOG_UNIMP, "setup_rt_frame: not implemented\n");
 }
 
 long do_sigreturn(CPUCRISState *env)
@@ -183,6 +183,6 @@ badframe:
 long do_rt_sigreturn(CPUCRISState *env)
 {
     trace_user_do_rt_sigreturn(env, 0);
-    fprintf(stderr, "CRIS do_rt_sigreturn: not implemented\n");
+    qemu_log_mask(LOG_UNIMP, "do_rt_sigreturn: not implemented\n");
     return -TARGET_ENOSYS;
 }
diff --git a/linux-user/microblaze/signal.c b/linux-user/microblaze/signal.c
index 712ee522b2..80950c2181 100644
--- a/linux-user/microblaze/signal.c
+++ b/linux-user/microblaze/signal.c
@@ -200,7 +200,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
                     target_siginfo_t *info,
                     target_sigset_t *set, CPUMBState *env)
 {
-    fprintf(stderr, "Microblaze setup_rt_frame: not implemented\n");
+    qemu_log_mask(LOG_UNIMP, "setup_rt_frame: not implemented\n");
 }
 
 long do_sigreturn(CPUMBState *env)
@@ -240,6 +240,6 @@ badframe:
 long do_rt_sigreturn(CPUMBState *env)
 {
     trace_user_do_rt_sigreturn(env, 0);
-    fprintf(stderr, "Microblaze do_rt_sigreturn: not implemented\n");
+    qemu_log_mask(LOG_UNIMP, "do_rt_sigreturn: not implemented\n");
     return -TARGET_ENOSYS;
 }
diff --git a/linux-user/nios2/signal.c b/linux-user/nios2/signal.c
index 4985dc2212..7d535065ed 100644
--- a/linux-user/nios2/signal.c
+++ b/linux-user/nios2/signal.c
@@ -203,7 +203,7 @@ give_sigsegv:
 long do_sigreturn(CPUNios2State *env)
 {
     trace_user_do_sigreturn(env, 0);
-    fprintf(stderr, "do_sigreturn: not implemented\n");
+    qemu_log_mask(LOG_UNIMP, "do_sigreturn: not implemented\n");
     return -TARGET_ENOSYS;
 }
 
diff --git a/linux-user/sparc/signal.c b/linux-user/sparc/signal.c
index 55e9d6f9b2..b4c60aa446 100644
--- a/linux-user/sparc/signal.c
+++ b/linux-user/sparc/signal.c
@@ -278,7 +278,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
                     target_siginfo_t *info,
                     target_sigset_t *set, CPUSPARCState *env)
 {
-    fprintf(stderr, "setup_rt_frame: not implemented\n");
+    qemu_log_mask(LOG_UNIMP, "setup_rt_frame: not implemented\n");
 }
 
 long do_sigreturn(CPUSPARCState *env)
@@ -357,7 +357,7 @@ segv_and_exit:
 long do_rt_sigreturn(CPUSPARCState *env)
 {
     trace_user_do_rt_sigreturn(env, 0);
-    fprintf(stderr, "do_rt_sigreturn: not implemented\n");
+    qemu_log_mask(LOG_UNIMP, "do_rt_sigreturn: not implemented\n");
     return -TARGET_ENOSYS;
 }