diff --git a/reactos/lib/sdk/crt/CMakeLists.txt b/reactos/lib/sdk/crt/CMakeLists.txt
index 131995951ec..c6ea7e15c2b 100644
--- a/reactos/lib/sdk/crt/CMakeLists.txt
+++ b/reactos/lib/sdk/crt/CMakeLists.txt
@@ -7,6 +7,10 @@ if(ARCH MATCHES i386)
     list(APPEND CHKSTK_SOURCE
         except/i386/chkstk_asm.s
         except/i386/chkstk_ms.s)
+elseif(ARCH MATCHES amd64)
+    list(APPEND CHKSTK_SOURCE
+        except/amd64/chkstk_asm.s
+        except/amd64/chkstk_ms.s)
 elseif(ARCH MATCHES powerpc)
     list(APPEND CHKSTK_SOURCE
         except/powerpc/chkstk_asm.s)
diff --git a/reactos/lib/sdk/crt/except/amd64/chkstk_asm.s b/reactos/lib/sdk/crt/except/amd64/chkstk_asm.s
index 113b45bc100..6f9e8773ac1 100644
--- a/reactos/lib/sdk/crt/except/amd64/chkstk_asm.s
+++ b/reactos/lib/sdk/crt/except/amd64/chkstk_asm.s
@@ -13,22 +13,19 @@
 /* CODE **********************************************************************/
 .code64
 
-PUBLIC MsgUnimplemented
-MsgUnimplemented:
-.asciz "WARNING:  %s at %s:%d is UNIMPLEMENTED!\n"
+EXTERN MsgUnimplemented:BYTE
 
-
-FUNC _chkstk
+FUNC __chkstk
     .endprolog
     UNIMPLEMENTED chkstk
     ret
-ENDFUNC _chkstk
+ENDFUNC __chkstk
 
-FUNC _alloca_probe
+FUNC __alloca_probe
     .endprolog
     UNIMPLEMENTED alloca_probe
     ret
-ENDFUNC _alloca_probe
+ENDFUNC __alloca_probe
 
 END
 /* EOF */