diff --git a/include/zephyr/posix/signal.h b/include/zephyr/posix/signal.h
index 827f1edff7ecd..09efaf1d0f147 100644
--- a/include/zephyr/posix/signal.h
+++ b/include/zephyr/posix/signal.h
@@ -52,9 +52,12 @@ extern "C" {
 
 BUILD_ASSERT(RTSIG_MAX >= 0);
 
+#if !defined(_SIGSET_T_DECLARED)
+#define _SIGSET_T_DECLARED
 typedef struct {
 	unsigned long sig[DIV_ROUND_UP(_NSIG, BITS_PER_LONG)];
 } sigset_t;
+#endif
 
 #ifndef SIGEV_NONE
 #define SIGEV_NONE 1