diff --git a/src/aclocal.m4 b/src/aclocal.m4
index 30299c8167f64fc3d93c8e78eb9b20f9c9dfef79..28c7ffd7c5b3797308a2efd1363263f03e498833 100644
--- a/src/aclocal.m4
+++ b/src/aclocal.m4
@@ -153,9 +153,10 @@ ECL_NEWLINE=LF
 ### 1.5) Can we guess how many characters are available for reading from
 ###      the FILE structure?
 ###          0 = no
-###          1 = (f)->_IO_read_end - (f)->_IO_read_ptr
-###          2 = (f)->_r
-###          3 = (f)->_cnt
+###          1 = __freadahead((f))
+###          2 = (f)->_IO_read_end - (f)->_IO_read_ptr
+###          3 = (f)->_r
+###          4 = (f)->_cnt
 ECL_FILE_CNT=0
 
 ###
@@ -626,21 +627,29 @@ AC_DEFUN(ECL_FILE_STRUCTURE,[
 AC_SUBST(ECL_FILE_CNT)
 if test -z "${ECL_FILE_CNT}"; then
 ECL_FILE_CNT=0
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+  #include <stdio.h>
+  #include <stdio_ext.h>
+]], [[
+  FILE *f = fopen("conftestval","w");
+  if (__freadahead((f)))
+    return 1;
+]])],[ECL_FILE_CNT=1],[])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]], [[
   FILE *f = fopen("conftestval","w");
   if ((f)->_IO_read_end - (f)->_IO_read_ptr)
     return 1;
-]])],[ECL_FILE_CNT=1],[])
+]])],[ECL_FILE_CNT=2],[])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]], [[
   FILE *f = fopen("conftestval","w");
   if ((f)->_r)
     return 1;
-]])],[ECL_FILE_CNT=2],[])
+]])],[ECL_FILE_CNT=3],[])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]], [[
   FILE *f = fopen("conftestval","w");
   if ((f)->_cnt)
     return 1;
-]])],[ECL_FILE_CNT=3],[])
+]])],[ECL_FILE_CNT=4],[])
 fi
 ])
 
diff --git a/src/configure b/src/configure
index 6f82dbf9c49797f9b49a3eae1091fd768a4c4030..57834b92bdc62d07fcd7f8e600bc1ddeb9de1c1e 100755
--- a/src/configure
+++ b/src/configure
@@ -5886,9 +5886,10 @@ ECL_NEWLINE=LF
 ### 1.5) Can we guess how many characters are available for reading from
 ###      the FILE structure?
 ###          0 = no
-###          1 = (f)->_IO_read_end - (f)->_IO_read_ptr
-###          2 = (f)->_r
-###          3 = (f)->_cnt
+###          1 = __freadahead((f))
+###          2 = (f)->_IO_read_end - (f)->_IO_read_ptr
+###          3 = (f)->_r
+###          4 = (f)->_cnt
 ECL_FILE_CNT=0
 
 ###
@@ -9250,6 +9251,29 @@ fi
 if test -z "${ECL_FILE_CNT}"; then
 ECL_FILE_CNT=0
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+  #include <stdio.h>
+  #include <stdio_ext.h>
+
+int
+main (void)
+{
+
+  FILE *f = fopen("conftestval","w");
+  if (__freadahead((f)))
+    return 1;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"
+then :
+  ECL_FILE_CNT=1
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <stdio.h>
 int
@@ -9266,7 +9290,7 @@ main (void)
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
-  ECL_FILE_CNT=1
+  ECL_FILE_CNT=2
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -9286,7 +9310,7 @@ main (void)
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
-  ECL_FILE_CNT=2
+  ECL_FILE_CNT=3
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -9306,7 +9330,7 @@ main (void)
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
-  ECL_FILE_CNT=3
+  ECL_FILE_CNT=4
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 fi
@@ -12810,4 +12834,3 @@ fi
 
 
 for i in $srcdir/c/*/; do mkdir -p c/`basename $i`; done
-
diff --git a/src/h/config-internal.h.in b/src/h/config-internal.h.in
index ebb2792fd3f436305d2543556b06afee28d2814c..952b41ee13d745afe28604585c91d94d68046582 100644
--- a/src/h/config-internal.h.in
+++ b/src/h/config-internal.h.in
@@ -176,12 +176,16 @@
 
 #undef FILE_CNT
 #if @ECL_FILE_CNT@ == 1
-#  define FILE_CNT(fp)  ((fp)->_IO_read_end - (fp)->_IO_read_ptr)
+#  include <stdio_ext.h>
+#  define FILE_CNT(fp)  (__freadahead((fp)))
 #endif
 #if @ECL_FILE_CNT@ == 2
-#  define FILE_CNT(fp)  ((fp)->_r)
+#  define FILE_CNT(fp)  ((fp)->_IO_read_end - (fp)->_IO_read_ptr)
 #endif
 #if @ECL_FILE_CNT@ == 3
+#  define FILE_CNT(fp)  ((fp)->_r)
+#endif
+#if @ECL_FILE_CNT@ == 4
 #  define FILE_CNT(fp)  ((fp)->_cnt)
 #endif
 
diff --git a/src/util/x86-linux-gnu.cross_config b/src/util/x86-linux-gnu.cross_config
index 03be03df58a5b579fbc5b749b6b924eaa3af3a18..d309b5c60ad65f590bd7121c9e45f455b56d8651 100644
--- a/src/util/x86-linux-gnu.cross_config
+++ b/src/util/x86-linux-gnu.cross_config
@@ -8,7 +8,7 @@ CL_LONG_BITS=32
 ECL_STACK_DIR=down
 ECL_BIGENDIAN=no
 ECL_NEWLINE=LF
-ECL_FILE_CNT=1
+ECL_FILE_CNT=2
 ECL_STDINT_HEADER="#include <stdint.h>"
 ECL_UINT8_T=uint8_t
 ECL_UINT16_T=uint16_t
diff --git a/src/util/x86_64-linux-gnu.cross_config b/src/util/x86_64-linux-gnu.cross_config
index e6d83dd73d349ece5ae235074f007c343feb42e3..0fbf2a9d8753f074057755025b53635e47cb1f7d 100644
--- a/src/util/x86_64-linux-gnu.cross_config
+++ b/src/util/x86_64-linux-gnu.cross_config
@@ -8,7 +8,7 @@ CL_LONG_BITS=64
 ECL_STACK_DIR=down
 ECL_BIGENDIAN=no
 ECL_NEWLINE=LF
-ECL_FILE_CNT=1
+ECL_FILE_CNT=2
 ECL_STDINT_HEADER="#include <stdint.h>"
 ECL_UINT8_T=uint8_t
 ECL_UINT16_T=uint16_t