diff --git a/loader/unknown_ext_chain_marmasm.asm b/loader/unknown_ext_chain_marmasm.asm
index 61f0182..6e9ee40 100644
--- a/loader/unknown_ext_chain_marmasm.asm
+++ b/loader/unknown_ext_chain_marmasm.asm
@@ -25,18 +25,11 @@
 ; jump to the next function in the call chain
 
 
-#if defined(_ARM64EC_)
-; arm64ec needs the SDK macros, which ksarm64.h gates on _M_ARM64EC. MARMASM
-; doesn't set that, so derive it from the _ARM64EC_ it does set.
-#define _M_ARM64EC 1
-#include "ksarm64.h"
-#endif
-
     GET gen_defines.asm
 
     EXTERN loader_log_asm_function_not_supported
 
-#if defined(_ARM64EC_)
+    IF :DEF: _ARM64EC_
 
 ; arm64ec apps can reach these through emulated x64, so each trampoline is an
 ; adjustor thunk: an entry thunk for x64 callers (jumps via __os_arm64x_x64_jump)
@@ -137,7 +130,7 @@ terminError$num
     NESTED_END
     MEND
 
-#else
+    ELSE
 
     IF AARCH_64==1
 
@@ -244,18 +237,18 @@ vkdev_ext$num FUNCTION
 
     ENDIF
 
-#endif
+    ENDIF
 
     AREA terminator_string_data, DATA, READONLY
 
 termin_error_string DCB "Function %s not supported for this physical device", 0
 
-#if defined(_ARM64EC_)
+    IF :DEF: _ARM64EC_
 ; the entry-thunk pointer wants 16-byte aligned functions, so set .text alignment here
     AREA |.text|, CODE, READONLY, ALIGN=4
-#else
+    ELSE
     AREA UnknownFunctionImpl, CODE, READONLY
-#endif
+    ENDIF
 
     PhysDevExtTramp 0
     PhysDevExtTramp 1