diff --git a/src/aclocal.m4 b/src/aclocal.m4
index 30299c816..28c7ffd7c 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>]], [[
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+  #include <stdio.h>
+  #include <stdio_ext.h>
+]], [[
   FILE *f = fopen("conftestval","w");
-  if ((f)->_IO_read_end - (f)->_IO_read_ptr)
+  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)->_r)
+  if ((f)->_IO_read_end - (f)->_IO_read_ptr)
     return 1;
 ]])],[ECL_FILE_CNT=2],[])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]], [[
   FILE *f = fopen("conftestval","w");
-  if ((f)->_cnt)
+  if ((f)->_r)
     return 1;
 ]])],[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=4],[])
 fi
 ])
 
diff --git a/src/configure b/src/configure
index 6f82dbf9c..57834b92b 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
 
 ###
@@ -9251,13 +9252,16 @@ 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.h>
+  #include <stdio_ext.h>
+
 int
 main (void)
 {
 
   FILE *f = fopen("conftestval","w");
-  if ((f)->_IO_read_end - (f)->_IO_read_ptr)
+  if (__freadahead((f)))
     return 1;
 
   ;
@@ -9277,7 +9281,7 @@ main (void)
 {
 
   FILE *f = fopen("conftestval","w");
-  if ((f)->_r)
+  if ((f)->_IO_read_end - (f)->_IO_read_ptr)
     return 1;
 
   ;
@@ -9297,7 +9301,7 @@ main (void)
 {
 
   FILE *f = fopen("conftestval","w");
-  if ((f)->_cnt)
+  if ((f)->_r)
     return 1;
 
   ;
@@ -9309,6 +9313,26 @@ then :
   ECL_FILE_CNT=3
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <stdio.h>
+int
+main (void)
+{
+
+  FILE *f = fopen("conftestval","w");
+  if ((f)->_cnt)
+    return 1;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"
+then :
+  ECL_FILE_CNT=4
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 fi
 
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for code to detect FP exceptions" >&5
@@ -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 ebb2792fd..952b41ee1 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 03be03df5..d309b5c60 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 e6d83dd73..0fbf2a9d8 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