diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2cb26b672dd..c0e24369fb1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2004-11-19  Alan Modra  <amodra@bigpond.net.au>
+
+	* config/rs6000/rs6000.c (function_arg): Don't return BLKmode regs.
+
 2004-11-18  Nicolas Pitre <nico@cam.org>
 
 	* config/arm/arm.c (const_double_needs_minipool): New function to
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 2e404efa8c7..7bf65545d8b 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -5525,6 +5525,9 @@ function_arg (CUMULATIVE_ARGS *cum, enum machine_mode mode,
 	  if (TARGET_32BIT && TARGET_POWERPC64)
 	    return rs6000_mixed_function_arg (mode, type, align_words);
 
+	  if (mode == BLKmode)
+	    mode = Pmode;
+
 	  return gen_rtx_REG (mode, GP_ARG_MIN_REG + align_words);
 	}
       else