diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e76658c78c9..802b4c680db 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,13 @@
+2005-10-30  Francois-Xavier Coudert  <coudert@clipper.ens.fr>
+
+	PR libfortran/20179
+	* gfortran.dg/mixed_io_1.f90: New test.
+	* gfortran.dg/mixed_io_1.c: New file.
+
+2005-10-30  Francois-Xavier Coudert  <coudert@clipper.ens.fr>
+
+	* gfortran.dg/malloc_free_1.f90: New test.
+
 2005-10-29  Hans-Peter Nilsson  <hp@axis.com>
 
 	* gcc.dg/nested-func-4.c: Require profiling -pg.
diff --git a/gcc/testsuite/gfortran.dg/mixed_io_1.c b/gcc/testsuite/gfortran.dg/mixed_io_1.c
new file mode 100644
index 00000000000..0f8d9cdcfbf
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/mixed_io_1.c
@@ -0,0 +1,4 @@
+#include <stdio.h>
+void cio_(void){
+  printf("12345");
+}
diff --git a/gcc/testsuite/gfortran.dg/mixed_io_1.f90 b/gcc/testsuite/gfortran.dg/mixed_io_1.f90
new file mode 100644
index 00000000000..0dc985cbbf6
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/mixed_io_1.f90
@@ -0,0 +1,5 @@
+! { dg-do run }
+! { dg-additional-sources mixed_io_1.c }
+      call cio
+      write(*,"(A)") '6789' ! { dg-output "123456789" }
+      end
diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index 85ea74080cc..0ea6adbb712 100644
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,11 @@
+2005-10-30  Francois-Xavier Coudert  <coudert@clipper.ens.fr>
+
+	PR libfortran/20179
+	* io/unix.c (flush_if_preconnected): New function.
+	* io/io.h: Add prototype for flush_if_preconnected.
+	* io/transfer.c (data_transfer_init): Use flush_if_preconnected
+	to workaround buggy mixed C-Fortran code.
+
 2005-10-30  Francois-Xavier Coudert  <coudert@clipper.ens.fr>
 
 	* Makefile.am: Add intrinsics/malloc.c file.
diff --git a/libgfortran/io/io.h b/libgfortran/io/io.h
index 90ee36cd73f..53a21b71f98 100644
--- a/libgfortran/io/io.h
+++ b/libgfortran/io/io.h
@@ -505,6 +505,9 @@ internal_proto(is_seekable);
 extern int is_preconnected (stream *);
 internal_proto(is_preconnected);
 
+extern void flush_if_preconnected (stream *);
+internal_proto(flush_if_preconnected);
+
 extern void empty_internal_buffer(stream *);
 internal_proto(empty_internal_buffer);
 
diff --git a/libgfortran/io/transfer.c b/libgfortran/io/transfer.c
index 391885b5e3c..0e1e099d00a 100644
--- a/libgfortran/io/transfer.c
+++ b/libgfortran/io/transfer.c
@@ -1379,6 +1379,9 @@ data_transfer_init (int read_flag)
       && current_unit->last_record == 0 && !is_preconnected(current_unit->s))
 	struncate(current_unit->s);
 
+  /* Bugware for badly written mixed C-Fortran I/O.  */
+  flush_if_preconnected(current_unit->s);
+
   current_unit->mode = g.mode;
 
   /* Set the initial value of flags.  */
diff --git a/libgfortran/io/unix.c b/libgfortran/io/unix.c
index 2026a364927..0fe8c4bad84 100644
--- a/libgfortran/io/unix.c
+++ b/libgfortran/io/unix.c
@@ -228,6 +228,23 @@ is_preconnected (stream * s)
     return 0;
 }
 
+/* If the stream corresponds to a preconnected unit, we flush the
+   corresponding C stream.  This is bugware for mixed C-Fortran codes
+   where the C code doesn't flush I/O before returning.  */
+void
+flush_if_preconnected (stream * s)
+{
+  int fd;
+
+  fd = ((unix_stream *) s)->fd;
+  if (fd == STDIN_FILENO)
+    fflush (stdin);
+  else if (fd == STDOUT_FILENO)
+    fflush (stdout);
+  else if (fd == STDERR_FILENO)
+    fflush (stderr);
+}
+
 
 /* Reset a stream after reading/writing. Assumes that the buffers have
    been flushed.  */