--- a/configure.in
+++ b/configure.in
@@ -312,6 +312,25 @@ AC_CHECK_FUNCS(atexit ioperm i386_set_io
 AC_REPLACE_FUNCS(getenv isfdtype sigprocmask snprintf \
     strcasestr strdup strndup strsep usleep sleep syslog vsyslog)
 
+dnl sys/io.h might provide ioperm but not inb,outb (like for
+dnl non i386/x32/x86_64 with musl libc)
+if test "${ac_cv_header_sys_io_h}" = "yes"; then
+  AC_MSG_CHECKING([for inb,outb (provided by sys/io.h)])
+  AC_LINK_IFELSE(
+    [AC_LANG_PROGRAM([[#include <sys/io.h>]],
+      [[inb(0);outb(0,0);]])],
+    [AC_MSG_RESULT([yes])
+      sane_cv_have_sys_io_h_with_inb_outb="yes"],
+    [AC_MSG_RESULT([no])
+      sane_cv_have_sys_io_h_with_inb_outb="no"
+      AC_MSG_WARN([sys/io.h does not provide inb,outb (non i386/x32/x86_64 arch?)])])
+  if test "$sane_cv_have_sys_io_h_with_inb_outb" = "yes"; then
+    AC_DEFINE(SANE_HAVE_SYS_IO_H_WITH_INB_OUTB, 1, [Define to 1 if you have the <sys/io.h> providing inb,outb.])
+  fi
+else
+  sane_cv_have_sys_io_h_with_inb_outb="no"
+fi
+
 SANE_PROTOTYPES
 
 if test "$ac_cv_header_os2_h" = "yes" ; then
--- a/include/sane/config.h.in
+++ b/include/sane/config.h.in
@@ -490,6 +484,9 @@
 /* SANE DLL minor number */
 #undef SANE_DLL_V_MINOR
 
+/* Define to 1 if you have the <sys/io.h> providing inb,outb. */
+#undef SANE_HAVE_SYS_IO_H_WITH_INB_OUTB
+
 /* SCSI command buffer size */
 #undef SCSIBUFFERSIZE
 
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -620,9 +620,9 @@ for be in ${BACKENDS}; do
     ;;
 
     qcam)
-    if test "${ac_cv_func_ioperm}" = "no" \
+    if ( test "${ac_cv_func_ioperm}" = "no" || test "${sane_cv_have_sys_io_h_with_inb_outb}" = "no" )\
       && test "${ac_cv_func__portaccess}" = "no"; then
-      echo "*** $be backend requires ioperm and portaccess functions - $DISABLE_MSG"
+      echo "*** $be backend requires (ioperm, inb and outb) or portaccess functions - $DISABLE_MSG"
       backend_supported="no"
     fi
     ;;
--- a/sanei/sanei_pio.c
+++ b/sanei/sanei_pio.c
@@ -61,6 +61,9 @@
 
 #ifdef HAVE_SYS_IO_H
 # include <sys/io.h>	/* use where available (glibc 2.x, for example) */
+# ifndef SANE_HAVE_SYS_IO_H_WITH_INB_OUTB
+#  define IO_SUPPORT_MISSING
+# endif
 #elif HAVE_ASM_IO_H
 # include <asm/io.h>		/* ugly, but backwards compatible */
 #elif HAVE_SYS_HW_H
--- a/sanei/sanei_ab306.c
+++ b/sanei/sanei_ab306.c
@@ -51,6 +51,9 @@
 
 #ifdef HAVE_SYS_IO_H
 # include <sys/io.h>	/* use where available (glibc 2.x, for example) */
+# ifndef SANE_HAVE_SYS_IO_H_WITH_INB_OUTB
+#  define IO_SUPPORT_MISSING
+# endif
 #elif HAVE_ASM_IO_H
 # include <asm/io.h>	/* ugly, but backwards compatible */
 #elif defined (__i386__)  && defined (__GNUC__)
--- a/sanei/sanei_pa4s2.c
+++ b/sanei/sanei_pa4s2.c
@@ -72,7 +72,10 @@
 #  if defined (__ICC) && __ICC >= 700
 #   define __GNUC__ 2
 #  endif
-# include <sys/io.h>
+#  include <sys/io.h>
+#  ifndef SANE_HAVE_SYS_IO_H_WITH_INB_OUTB
+#   define IO_SUPPORT_MISSING
+#  endif
 #  if defined (__ICC) && __ICC >= 700
 #   undef __GNUC__
 #  elif defined(__ICC) && defined(HAVE_ASM_IO_H)
--- a/sanei/sanei_pp.c
+++ b/sanei/sanei_pp.c
@@ -94,6 +94,9 @@
 #   define __GNUC__ 2
 #  endif
 #  include <sys/io.h>
+#  ifndef SANE_HAVE_SYS_IO_H_WITH_INB_OUTB
+#   define IO_SUPPORT_MISSING
+#  endif
 #  if defined (__ICC) && __ICC >= 700
 #   undef __GNUC__
 #  elif defined(__ICC) && defined(HAVE_ASM_IO_H)