diff --git a/crypto/CMakeLists.txt b/crypto/CMakeLists.txt
index e57bb600..cf2973ad 100644
--- a/crypto/CMakeLists.txt
+++ b/crypto/CMakeLists.txt
@@ -237,9 +237,16 @@ if(neon)
 endif()
 
 test_compile_with_flags(HAVE_ARM_DIT
-  GNU_FLAGS -march=armv8.4-a
   TEST_SOURCE "
-    int main(void) { asm volatile(\"msr dit, %0\" :: \"r\"(1)); }"
+    #ifndef __aarch64__
+    #error make sure this only even tries to work on AArch64
+    #endif
+    #include <stdint.h>
+    int main(void) {
+      register uint64_t one asm(\"x8\");
+      one = 1;
+      asm volatile(\".inst 0xd51b42a8\" :: \"r\"(one));
+    }"
   ADD_SOURCES_IF_SUCCESSFUL enable_dit.c)
 
 set(HAVE_AES_NI ${HAVE_AES_NI} PARENT_SCOPE)
diff --git a/crypto/enable_dit.c b/crypto/enable_dit.c
index 7c9ec4b4..65e57078 100644
--- a/crypto/enable_dit.c
+++ b/crypto/enable_dit.c
@@ -20,5 +20,9 @@ void enable_dit(void)
 {
     if (!platform_dit_available())
         return;
-    asm volatile("msr dit, %0" :: "r"(1));
+    register uint64_t one asm("x8");
+    one = 1;
+    // This is the binary encoding of "msr dit, x8". You can check via, e.g.,
+    // echo "msr dit,x8" | llvm-mc -triple aarch64 -mattr=+dit -show-encoding
+    asm volatile(".inst 0xd51b42a8" :: "r"(one));
 }