diff --git a/funcs/func_callerid.c b/funcs/func_callerid.c
index e026d67a9b0fdeefa4cc5da2d755c9b26eeb5973..c8fd1bb9e2193d1cceb10dd6bea1ad8e8bc94b6c 100644
--- a/funcs/func_callerid.c
+++ b/funcs/func_callerid.c
@@ -60,7 +60,9 @@ static int callerid_read(struct ast_channel *chan, const char *cmd, char *data,
 {
 	char *opt = data;
 
-	/* XXX we are not always clearing the buffer. Is this correct ? */
+	if (!chan)
+		return -1;
+
 	if (strchr(opt, '|')) {
 		char name[80], num[80];
 
@@ -116,7 +118,7 @@ static int callerid_read(struct ast_channel *chan, const char *cmd, char *data,
 static int callerid_write(struct ast_channel *chan, const char *cmd, char *data,
 			  const char *value)
 {
-	if (!value)
+	if (!value || !chan)
 		return -1;
 
 	if (!strncasecmp("all", data, 3)) {
diff --git a/funcs/func_cdr.c b/funcs/func_cdr.c
index 4f1c457c0ff10bf459dc406b01157ea64c893848..951e980ae4deb91cf5dda0bf18037bdaed659817 100644
--- a/funcs/func_cdr.c
+++ b/funcs/func_cdr.c
@@ -59,7 +59,7 @@ static int cdr_read(struct ast_channel *chan, const char *cmd, char *parse,
 {
 	char *ret;
 	struct ast_flags flags = { 0 };
-	struct ast_cdr *cdr = chan->cdr;
+	struct ast_cdr *cdr = chan ? chan->cdr : NULL;
 	AST_DECLARE_APP_ARGS(args,
 			     AST_APP_ARG(variable);
 			     AST_APP_ARG(options);
@@ -96,7 +96,7 @@ static int cdr_write(struct ast_channel *chan, const char *cmd, char *parse,
 			     AST_APP_ARG(options);
 	);
 
-	if (ast_strlen_zero(parse) || !value)
+	if (ast_strlen_zero(parse) || !value || !chan)
 		return -1;
 
 	AST_STANDARD_APP_ARGS(args, parse);
diff --git a/funcs/func_groupcount.c b/funcs/func_groupcount.c
index 2be3f831d99d4c6acc32ced55a6c6395d62c9145..fb7ec57e293dc6c33d2114a088792e3df55c8477 100644
--- a/funcs/func_groupcount.c
+++ b/funcs/func_groupcount.c
@@ -158,6 +158,9 @@ static int group_list_function_read(struct ast_channel *chan, const char *cmd,
 	char tmp1[1024] = "";
 	char tmp2[1024] = "";
 
+	if (!chan)
+		return -1;
+
 	headp = &chan->varshead;
 	AST_LIST_TRAVERSE(headp, current, entries) {
 		if (!strncmp(ast_var_name(current), GROUP_CATEGORY_PREFIX "_", strlen(GROUP_CATEGORY_PREFIX) + 1)) {
diff --git a/funcs/func_timeout.c b/funcs/func_timeout.c
index a400a95ab80304a35e5e409328c7bd36947cb6ca..1da11e54a60066e04314bef9d937fa0b5a52648d 100644
--- a/funcs/func_timeout.c
+++ b/funcs/func_timeout.c
@@ -46,6 +46,9 @@ static int timeout_read(struct ast_channel *chan, const char *cmd, char *data,
 {
 	time_t myt;
 
+	if (!chan)
+		return -1;
+
 	if (!data) {
 		ast_log(LOG_ERROR, "Must specify type of timeout to get.\n");
 		return -1;
@@ -91,6 +94,9 @@ static int timeout_write(struct ast_channel *chan, const char *cmd, char *data,
 	char timestr[64];
 	struct tm myt;
 
+	if (!chan)
+		return -1;
+
 	if (!data) {
 		ast_log(LOG_ERROR, "Must specify type of timeout to set.\n");
 		return -1;