diff --git a/.gitignore b/.gitignore
index 31205dc..a040def 100644
--- a/.gitignore
+++ b/.gitignore
@@ -60,3 +60,4 @@ test_alignment
 /compile_commands.json
 /.cache/
 /scratch.c
+/configure~
diff --git a/m4/ax_cache_size.m4 b/m4/ax_cache_size.m4
index a11344a..f9568c3 100644
--- a/m4/ax_cache_size.m4
+++ b/m4/ax_cache_size.m4
@@ -59,7 +59,7 @@ AC_DEFUN([AX_CACHE_SIZE],
 
     else
         # Try CPUID (mostly for Linux without sysfs or during cross-compilation)
-        if test "x$ax_cv_cpu_vendor" != "xIntel"; then
+        if test "x$ax_cv_cpu_vendor" != "xUnknown" && test "x$ax_cv_cpu_vendor" != "xunknown" && test "x$ax_cv_cpu_vendor" != "xIntel"; then
             AX_GCC_X86_CPUID(0x80000000)
             cpu_exthigh=`echo $ax_cv_gcc_x86_cpuid_0x80000000 | cut -d ":" -f 1`
             if test "x$cpu_exthigh" \> "x80000004"; then