diff --git a/config/kernel-in-compat-syscall.m4 b/config/kernel-in-compat-syscall.m4
deleted file mode 100644
index baaac8c4f..000000000
--- a/config/kernel-in-compat-syscall.m4
+++ /dev/null
@@ -1,24 +0,0 @@
-dnl #
-dnl # 4.5 API change
-dnl # Added in_compat_syscall() which can be overridden on a per-
-dnl # architecture basis.  Prior to this is_compat_task() was the
-dnl # provided interface.
-dnl #
-AC_DEFUN([ZFS_AC_KERNEL_SRC_IN_COMPAT_SYSCALL], [
-	ZFS_LINUX_TEST_SRC([in_compat_syscall], [
-		#include <linux/compat.h>
-	],[
-		in_compat_syscall();
-	])
-])
-
-AC_DEFUN([ZFS_AC_KERNEL_IN_COMPAT_SYSCALL], [
-	AC_MSG_CHECKING([whether in_compat_syscall() is available])
-	ZFS_LINUX_TEST_RESULT([in_compat_syscall], [
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_IN_COMPAT_SYSCALL, 1,
-		    [in_compat_syscall() is available])
-	],[
-		AC_MSG_RESULT(no)
-	])
-])
diff --git a/config/kernel.m4 b/config/kernel.m4
index dfbd82c81..ed6007a19 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -117,7 +117,6 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_KUID_HELPERS
 	ZFS_AC_KERNEL_SRC_RENAME
 	ZFS_AC_KERNEL_SRC_USERNS_CAPABILITIES
-	ZFS_AC_KERNEL_SRC_IN_COMPAT_SYSCALL
 	ZFS_AC_KERNEL_SRC_KTIME
 	ZFS_AC_KERNEL_SRC_TOTALRAM_PAGES_FUNC
 	ZFS_AC_KERNEL_SRC_TOTALHIGH_PAGES
@@ -249,7 +248,6 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_KUID_HELPERS
 	ZFS_AC_KERNEL_RENAME
 	ZFS_AC_KERNEL_USERNS_CAPABILITIES
-	ZFS_AC_KERNEL_IN_COMPAT_SYSCALL
 	ZFS_AC_KERNEL_KTIME
 	ZFS_AC_KERNEL_TOTALRAM_PAGES_FUNC
 	ZFS_AC_KERNEL_TOTALHIGH_PAGES
diff --git a/include/os/linux/kernel/linux/vfs_compat.h b/include/os/linux/kernel/linux/vfs_compat.h
index e55c216ac..aa8f4cc97 100644
--- a/include/os/linux/kernel/linux/vfs_compat.h
+++ b/include/os/linux/kernel/linux/vfs_compat.h
@@ -312,11 +312,7 @@ static inline int
 zpl_is_32bit_api(void)
 {
 #ifdef CONFIG_COMPAT
-#ifdef HAVE_IN_COMPAT_SYSCALL
 	return (in_compat_syscall());
-#else
-	return (is_compat_task());
-#endif
 #else
 	return (BITS_PER_LONG == 32);
 #endif