diff --git a/configure.in b/configure.in
index 2a7ade1b..7f6ddc60 100644
--- a/configure.in
+++ b/configure.in
@@ -266,9 +266,9 @@ OUR_CFLAGS_HEAD='-I$(top_builddir) -I$(srcdir)/include -I$(top_srcdir)/include'
 if test "x$debug" = xtrue; then
 	OUR_CFLAGS_HEAD="$OUR_CFLAGS_HEAD -g -DDEBUG"
 else
-	OUR_CFLAGS_HEAD="$OUR_CFLAGS_HEAD -O2 -DNDEBUG"
+	OUR_CFLAGS_HEAD="$OUR_CFLAGS_HEAD -DNDEBUG"
 	if test "x$GCC" = xyes; then
-		OUR_CFLAGS_HEAD="$OUR_CFLAGS_HEAD -O3 -fomit-frame-pointer -funroll-loops -finline-functions -Wall -W -Winline -DFLaC__INLINE=__inline__"
+		OUR_CFLAGS_HEAD="$OUR_CFLAGS_HEAD -O3 -funroll-loops -finline-functions -Wall -W -Winline -DFLaC__INLINE=__inline__"
 	fi
 fi
 CFLAGS="$OUR_CFLAGS_HEAD $CFLAGS"
diff --git a/src/libFLAC++/libFLAC++.m4 b/src/libFLAC++/libFLAC++.m4
index 2f5af24e..3d7a14ee 100644
--- a/src/libFLAC++/libFLAC++.m4
+++ b/src/libFLAC++/libFLAC++.m4
@@ -29,7 +29,7 @@ AC_ARG_ENABLE(libFLACPPtest, [  --disable-libFLACPPtest       Do not try to comp
   elif test "x$libFLACPP_prefix" != "x" ; then
     LIBFLACPP_CFLAGS="-I$libFLACPP_prefix/include"
   elif test "$prefix" != "xNONE"; then
-    LIBFLACPP_CFLAGS="-I$prefix/include"
+    LIBFLACPP_CFLAGS=""
   fi
 
   LIBFLACPP_CFLAGS="$LIBFLACPP_CFLAGS $LIBFLAC_CFLAGS"
diff --git a/src/libFLAC/libFLAC.m4 b/src/libFLAC/libFLAC.m4
index e26d0a8b..ee589e2a 100644
--- a/src/libFLAC/libFLAC.m4
+++ b/src/libFLAC/libFLAC.m4
@@ -28,7 +28,7 @@ AC_ARG_ENABLE(libFLACtest, [  --disable-libFLACtest       Do not try to compile
   elif test "x$libFLAC_prefix" != "x" ; then
     LIBFLAC_CFLAGS="-I$libFLAC_prefix/include"
   elif test "$prefix" != "xNONE"; then
-    LIBFLAC_CFLAGS="-I$prefix/include"
+    LIBFLAC_CFLAGS=""
   fi
 
   AC_MSG_CHECKING(for libFLAC)