diff --git a/src/configure.in b/src/configure.in
index d675930..f1720ce 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -776,6 +776,7 @@
       ldflags_save=$LDFLAGS
       CFLAGS="$CFLAGS $perlcppflags"
       LIBS="$LIBS $perllibs"
+      perlldflags=`echo "$perlldflags" | sed -e 's/^ *//g'`
       LDFLAGS="$perlldflags $LDFLAGS"
       AC_TRY_LINK(,[ ],
 	     AC_MSG_RESULT(yes); perl_ok=yes,
@@ -789,7 +790,9 @@
 	  PERL_CFLAGS=`echo "$perlcppflags" | sed -e 's/-pipe //' -e 's/-W[[^ ]]*//'`
 	fi
 	if test "X$perlldflags" != "X"; then
-	  LDFLAGS="$perlldflags $LDFLAGS"
+	  if test "X`echo \"$LDFLAGS\" | grep -F -e \"$perlldflags\"`" = "X"; then
+	    LDFLAGS="$perlldflags $LDFLAGS"
+	  fi
 	fi
 	PERL_LIBS=$perllibs
 	PERL_SRC="auto/if_perl.c if_perlsfio.c"
@@ -1546,7 +1549,9 @@
 	  dnl configure, so strip these flags first (if present)
 	  rubyldflags=`echo "$rubyldflags" | sed -e 's/-arch\ ppc//' -e 's/-arch\ i386//' -e 's/-arch\ x86_64//'`
 	  if test "X$rubyldflags" != "X"; then
-	    LDFLAGS="$rubyldflags $LDFLAGS"
+	    if test "X`echo \"$LDFLAGS\" | grep -F -e \"$rubyldflags\"`" = "X"; then
+	      LDFLAGS="$rubyldflags $LDFLAGS"
+	    fi
 	  fi
 	fi
 	RUBY_SRC="if_ruby.c"
@@ -3719,7 +3724,7 @@
   dnl And undefine it first to avoid a warning.
   AC_MSG_CHECKING(whether we need -D_FORTIFY_SOURCE=1)
   if test "$gccmajor" -gt "3"; then
-    CFLAGS=`echo "$CFLAGS" | sed -e 's/-Wp,-D_FORTIFY_SOURCE=.//g' -e 's/-D_FORTIFY_SOURCE=.//g' -e 's/$/ -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1/'`
+    CFLAGS=`echo "$CFLAGS" | sed -e 's/ *-Wp,-D_FORTIFY_SOURCE=.//g' -e 's/ *-D_FORTIFY_SOURCE=.//g' -e 's/ *-U_FORTIFY_SOURCE//g' -e 's/$/ -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1/'`
     AC_MSG_RESULT(yes)
   else
     AC_MSG_RESULT(no)
@@ -3734,7 +3739,7 @@
 LINK_AS_NEEDED=
 # Check if linker supports --as-needed and --no-as-needed options
 if $CC -Wl,--help 2>/dev/null | grep as-needed > /dev/null; then
-  LDFLAGS="$LDFLAGS -Wl,--as-needed"
+  LDFLAGS=`echo "$LDFLAGS" | sed -e 's/ *-Wl,--as-needed//g' | sed -e 's/$/ -Wl,--as-needed/'`
   LINK_AS_NEEDED=yes
 fi
 if test "$LINK_AS_NEEDED" = yes; then