diff --git a/src/stub/fold_elf86.asm b/src/stub/fold_elf86.asm
index 44a01c03..89593b6c 100644
--- a/src/stub/fold_elf86.asm
+++ b/src/stub/fold_elf86.asm
@@ -181,11 +181,14 @@ L20:  ; move envp
 L30:  ; process auxv
         lodsd  ; a_type
         stosd
-        test eax, eax  ; AT_NULL ?  [flags: Zero, Sign, Parity; C=0, V=0]
+        cmp al, 32
+        jae L32  ; prevent aliasing of 'btr' when 32<=a_type
         btr edx, eax  ; no longer need a slot of type eax  [Carry only]
+L32:
+        test eax, eax  ; AT_NULL ?  [flags: Zero, Sign, Parity; C=0, V=0]
         lodsd
         stosd
-        jne L30  ; checks only Zero bit of flags
+        jnz L30  ; checks only Zero bit of flags
 
         sub edi, byte 8  ; backup to AT_NULL
         add ecx, ecx  ; two words per auxv