diff --git a/src/configure.in b/src/configure.in
index e1ec411da7178e146b41f43a2f22b5da917df291..68389199601e2c0b93379086c0dd4918ffbc0350 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -1,4 +1,4 @@
-AC_REVISION("$Id: configure.in,v 1.333 1999/11/24 21:40:32 hubbe Exp $")
+AC_REVISION("$Id: configure.in,v 1.334 1999/11/29 16:08:50 grubba Exp $")
 AC_INIT(interpret.c)
 AC_CONFIG_HEADER(machine.h)
 
@@ -276,9 +276,19 @@ LD='$(CC) $(CFLAGS)'
 case "$pike_cv_sys_os" in
   SCO*)
      case "$CFLAGS" in
-       *-belf*) ;;
+        *-belf*) 
+          AC_SYS_COMPILER_FLAG(-belf,sco_belf_option,CFLAGS,[],[
+            case "$LDFLAGS" in
+              *-belf*) ;;
+              *)
+                echo "Adding -belf option to ldflags."
+                LDFLAGS="$LDFLAGS -belf"
+              ;;
+            esac
+          ])
+       ;;
        *)
-	  AC_SYS_COMPILER_FLAG(-belf,belf,CFLAGS)
+	 AC_SYS_COMPILER_FLAG(-belf,belf,CFLAGS)
        ;;
      esac
      case "$LDFLAGS" in
@@ -297,10 +307,16 @@ case "$pike_cv_sys_os" in
     LD="$BINDIR/smartlink shlicc"
   ;;
   UnixWare*)
-    if test "$GCC" != "yes"; then
-      # We are using built-in inline function
-      CFLAGS="$CFLAGS -Kalloca"
-    fi
+    case "$CFLAGS" in
+      *-Kalloca*) ;;
+      *)
+	if test "$GCC" != "yes"; then
+	  # We are using built-in inline function
+	  CFLAGS="$CFLAGS -Kalloca"
+	  CXX="$CXX -DNO_CPLUSPLUS_ALLOCA"
+	fi
+      ;;
+    esac
   ;;
 esac
 
@@ -729,15 +745,22 @@ esac
 #  AC_SYS_CPU_COMPILER_FLAG(sun4u,-Xpipe=super,ultrasparc,OPTIMIZE)
 
   case "${CFLAGS-} $OPTIMIZE" in
-     *-O*) ;;
-     *+O*) ;;
-     *-fast*) ;;
-     *)
-      AC_SYS_COMPILER_FLAG(-O2,O2,OPTIMIZE)
-      if test "x$pike_cv_option_O2" != "xyes"; then
-        AC_SYS_COMPILER_FLAG(-O,O,OPTIMIZE)
-      fi
-     ;;
+    *-O*) ;;
+    *+O*) ;;
+    *-fast*) ;;
+    *)
+      case "$pike_cv_sys_os:$GCC" in
+        UnixWare*:no)
+	  OPTIMIZE=""
+	;;
+	*)
+	  AC_SYS_COMPILER_FLAG(-O2,O2,OPTIMIZE)
+	  if test "x$pike_cv_option_O2" != "xyes"; then
+	    AC_SYS_COMPILER_FLAG(-O,O,OPTIMIZE)
+	  fi
+	;;
+      esac
+    ;;
   esac
  fi
  fi