diff --git a/CHANGES b/CHANGES
index 1d38730..b976bad 100644
--- a/CHANGES
+++ b/CHANGES
@@ -27,6 +27,11 @@ corrections:
 
 	minor corrections in doc (2x)
 
+porting:
+	building socat on systems that predefined the CFLAGS environment to
+	contain -Wall failed (esp.RedHat). Thanks to Paul Wouters for reporting
+	this problem and to Simon Matter for providing the patch
+
 ####################### V 2.0.0-b7:
 
 security:
diff --git a/compat.h b/compat.h
index 15c9452..dd198fe 100644
--- a/compat.h
+++ b/compat.h
@@ -261,7 +261,10 @@
 #  endif
 #endif
 
-/* might be checked in later versions */
+#if !defined(HAVE_BASIC_OFF_T) || !HAVE_BASIC_OFF_T
+#  undef HAVE_BASIC_OFF_T
+#  define HAVE_BASIC_OFF_T 5 /*long*/
+#endif
 #ifndef F_off
 #  if HAVE_BASIC_OFF_T==3
 #     define F_off "%d"
diff --git a/configure.in b/configure.in
index 527e32c..949a18b 100644
--- a/configure.in
+++ b/configure.in
@@ -84,7 +84,7 @@ AC_CHECK_FUNC(setsockopt, , AC_CHECK_LIB(socket, setsockopt))
 dnl Check for hstrerror prototype
 AC_MSG_CHECKING(for hstrerror prototype)
 AC_CACHE_VAL(sc_cv_have_prototype_hstrerror,
-[CFLAGS1="$CFLAGS"; CFLAGS="-Werror -O0 $CFLAGS1";
+[CFLAGS1="$CFLAGS"; CFLAGS="-Werror -O0 $(echo "$CFLAGS1" | sed -e 's@-Wall@@g')";
  AC_TRY_COMPILE([#include <netdb.h>],[hstrerror();],
  [sc_cv_have_prototype_hstrerror=no],
  [sc_cv_have_prototype_hstrerror=yes]);
@@ -1312,7 +1312,7 @@ dnl   output values: 1..short, 2..unsigned short, 3..int, 4..u-int,
 dnl                  5..long, 6..u-long; others not yet supported
 define(AC_BASIC_TYPE,[
 AC_CACHE_CHECK(for equivalent simple type of $2, $4,
-[CFLAGS1="$CFLAGS"; CFLAGS="-Werror -O0 $CFLAGS1"
+[CFLAGS1="$CFLAGS"; CFLAGS="-Werror -O0 $(echo "$CFLAGS1" | sed -e 's@-Wall@@g')"
  AC_TRY_COMPILE([$1],[$2 u; short v; &u==&v;],
  [$4="1 /* short */"],
  [AC_TRY_COMPILE([$1],[$2 u; unsigned short v; &u==&v;],
@@ -1344,7 +1344,7 @@ dnl arg4: output variable, values see AC_BASIC_TYPE
 dnl arg5: cache variable (might be constructed automatically)
 define(AC_TYPEOF_COMPONENT,[
 AC_CACHE_CHECK(for basic type of $2.$3, $5,
-[CFLAGS1="$CFLAGS"; CFLAGS="-Werror -O0 $CFLAGS1"
+[CFLAGS1="$CFLAGS"; CFLAGS="-Werror -O0 $(echo "$CFLAGS1" | sed -e 's@-Wall@@g')"
 AC_TRY_COMPILE([$1],[$2 u;short v; &u.$3==&v;],
 [$5="1 /* short */"],
 [AC_TRY_COMPILE([$1],[$2 u; unsigned short v; &u.$3==&v;],