diff --git a/README b/README
index 9b848b47940c7d034171bb8ad934f39f613babc8..fd73dac37f25338c485d51f4c9bea4f2f09204ab 100644
--- a/README
+++ b/README
@@ -63,13 +63,13 @@ The default installation path is also the build directory. This can be changed v
 
   --prefix=PREFIX         install architecture-independent files in PREFIX.
 
-Default library mode is static. Change this via
+Default library mode is to install static and shared libraries. Change this via
 
-  --enable-shared=??
+  --enable-shared=?? and/or --enable-static=??
 
-where ?? is "yes" or "no". Setting "yes" will additionally install shared ".so.???" libraries.
+where ?? is "yes" or "no".
 
-We recommend setting the environment variable "CFLAGS", so that "configure" does NOT automatically substitute a "-g" debugging option while compiling, as well as using the highest possible optimization flag "-O???" during a build of (non-debug) libraries.
+We recommend setting the environment variables "CFLAGS" and "FFLAGS" to "", so that "configure" does NOT automatically substitute a "-g" debugging option while compiling, as well as using the highest possible optimization flag "-O???" during a build of (non-debug) libraries.
 
 
 
diff --git a/configure.ac b/configure.ac
index 03a8513dae20088c3f2f9572a6d8fbc057ab5638..d58b8c2f1c27587e7faeabacc4d4470ea435356b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -28,7 +28,6 @@ AC_PROG_LN_S
 AC_PROG_CC
 AC_PROG_F77
 
-AC_DISABLE_SHARED
 AC_PROG_LIBTOOL
 
 # change the installation directory. This could surely be done more elegantly...
@@ -51,7 +50,7 @@ AC_PATH_XTRA
 
 # Checks for header files.
 AC_HEADER_STDC
-AC_CHECK_HEADERS([malloc.h unistd.h X11/Xlib.h X11/Xutil.h],,
+AC_CHECK_HEADERS([malloc.h unistd.h X11/Xlib.h X11/Xutil.h X11/extensions/Xext.h],,
 		 [AC_MSG_ERROR([Exiting...])])
 AC_CHECK_HEADERS([GL/gl.h GL/glx.h rpc/xdr.h],,[AC_MSG_ERROR([Exiting...])])