diff --git a/ChangeLog b/ChangeLog
index b4aff9ba0..eb725d4de 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Aug 21 21:42:14 CEST 2007 (tk)
+----------------------------------
+  * libclamav/rtf.c: fix possible NULL dereference (bb#611)
+
 Tue Aug 21 21:39:06 CEST 2007 (tk)
 ----------------------------------
   * libclamav/ole2_extract.c: properly initialise hdr.max_block_no (bb#603)
diff --git a/libclamav/rtf.c b/libclamav/rtf.c
index 33c24eae2..e5a0f77ad 100644
--- a/libclamav/rtf.c
+++ b/libclamav/rtf.c
@@ -606,7 +606,9 @@ int cli_scanrtf(int desc, cli_ctx *ctx)
 											 return ret;
 										}
 									if(( ret = state.cb_process(&state, ptr, use) )) {
-										state.cb_end(&state,ctx);
+										if(state.cb_end) {
+											state.cb_end(&state,ctx);
+										}
 										SCAN_CLEANUP;
 										return ret;
 									}
@@ -677,6 +679,7 @@ int cli_scanrtf(int desc, cli_ctx *ctx)
 						if(action != -1) {
 							if(state.cb_data && state.cb_end) {/* premature end of previous block */
 								state.cb_end(&state,ctx);
+								state.cb_begin = NULL;
 								state.cb_end = NULL;
 								state.cb_data = NULL;
 							}