diff --git a/Userland/Libraries/LibC/setjmp.h b/Userland/Libraries/LibC/setjmp.h
index 2c998b4237..3b4c7d9a75 100644
--- a/Userland/Libraries/LibC/setjmp.h
+++ b/Userland/Libraries/LibC/setjmp.h
@@ -26,7 +26,7 @@ struct __jmp_buf {
     uint32_t ebp;
     uint32_t esp;
     uint32_t eip;
-#elif __x86_64__
+#elif defined(__x86_64__)
     uint64_t rbx;
     uint64_t r12;
     uint64_t r13;
@@ -35,7 +35,7 @@ struct __jmp_buf {
     uint64_t rbp;
     uint64_t rsp;
     uint64_t rip;
-#elif __aarch64__
+#elif defined(__aarch64__)
     // FIXME: This is likely incorrect.
     uint64_t regs[22];
 #else
@@ -54,9 +54,9 @@ typedef struct __jmp_buf sigjmp_buf[1];
 #ifdef __cplusplus
 #    ifdef __i386__
 static_assert(sizeof(struct __jmp_buf) == 32, "struct __jmp_buf unsynchronized with i386/setjmp.S");
-#    elif __x86_64__
+#    elif defined(__x86_64__)
 static_assert(sizeof(struct __jmp_buf) == 72, "struct __jmp_buf unsynchronized with x86_64/setjmp.S");
-#    elif __aarch64__
+#    elif defined(__aarch64__)
 static_assert(sizeof(struct __jmp_buf) == 184, "struct __jmp_buf unsynchronized with aarch64/setjmp.S");
 #    else
 #        error