diff --git a/arch/arc/core/thread.c b/arch/arc/core/thread.c
index ec402cabb19..137ce05abc8 100644
--- a/arch/arc/core/thread.c
+++ b/arch/arc/core/thread.c
@@ -16,9 +16,6 @@
 #include <kernel_structs.h>
 #include <offsets_short.h>
 #include <wait_q.h>
-#ifdef CONFIG_INIT_STACKS
-#include <string.h>
-#endif /* CONFIG_INIT_STACKS */
 
 #ifdef CONFIG_USERSPACE
 #include <arch/arc/v2/mpu/arc_core_mpu.h>
diff --git a/arch/posix/core/thread.c b/arch/posix/core/thread.c
index e99f6365109..bfe1368f4d2 100644
--- a/arch/posix/core/thread.c
+++ b/arch/posix/core/thread.c
@@ -13,10 +13,6 @@
  * architecture
  */
 
-#ifdef CONFIG_INIT_STACKS
-#include <string.h>
-#endif /* CONFIG_INIT_STACKS */
-
 #include <toolchain.h>
 #include <kernel_structs.h>
 #include <wait_q.h>
diff --git a/arch/x86/core/ia32/thread.c b/arch/x86/core/ia32/thread.c
index d5ea8971cdb..68563be7235 100644
--- a/arch/x86/core/ia32/thread.c
+++ b/arch/x86/core/ia32/thread.c
@@ -12,10 +12,6 @@
  * processor architecture.
  */
 
-#ifdef CONFIG_INIT_STACKS
-#include <string.h>
-#endif /* CONFIG_INIT_STACKS */
-
 #include <toolchain.h>
 #include <linker/sections.h>
 #include <kernel_structs.h>
diff --git a/arch/xtensa/core/thread.c b/arch/xtensa/core/thread.c
index 06ee316a354..5a7a3075d6d 100644
--- a/arch/xtensa/core/thread.c
+++ b/arch/xtensa/core/thread.c
@@ -3,9 +3,6 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#ifdef CONFIG_INIT_STACKS
-#include <string.h>
-#endif /* CONFIG_INIT_STACKS */
 #ifdef CONFIG_DEBUG
 #include <sys/printk.h>
 #endif