--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S	
+++ a/sysdeps/x86_64/multiarch/strcmp-avx2.S	
@@ -256,6 +256,12 @@ L(next_3_vectors):
 	vpmovmskb %ymm0, %ecx
 	testl	%ecx, %ecx
 	jne	L(return_3_vec_size)
+	/* Check if VEC_SIZE * 4 already exceeded max compare count %r11 */
+# ifdef USE_AS_STRNCMP
+	movq    $(VEC_SIZE * 4), %rdx
+	cmpq    %r11, %rdx
+	jae     L(zero)
+# endif
 L(main_loop_header):
 	leaq	(VEC_SIZE * 4)(%rdi), %rdx
 	movl	$PAGE_SIZE, %ecx