diff --git a/c/src/lib/libcpu/powerpc/ChangeLog b/c/src/lib/libcpu/powerpc/ChangeLog
index e48e309e81..b9ae8f072d 100644
--- a/c/src/lib/libcpu/powerpc/ChangeLog
+++ b/c/src/lib/libcpu/powerpc/ChangeLog
@@ -1,3 +1,10 @@
+2007-12-10	Till Straumann <strauman@slac.stanford.edu>
+
+	* new-exceptions/bspsupport/ppc_exc_hdl.c: make sure
+	RI is set in the exception frame and panic if it isn't
+	(state info might have been lost). This only affects
+	classic PPC.
+
 2007-12-10	Till Straumann <strauman@slac.stanford.edu>
 
 	* new-exceptions/bspsupport/README,
diff --git a/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c b/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c
index 7d33088a57..a88b2fb371 100644
--- a/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c
+++ b/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c
@@ -97,6 +97,12 @@ int          rval = 1;
 		rval = 0;
 	}
 
+	if ( (ppc_exc_msr_bits ^ f->EXC_SRR1) & MSR_RI ) {
+		printk("unrecoverable exception (RI was clear), spinning to death.\n");
+		while (1)
+			;
+	}
+
 	return rval;
 }