diff --git a/common/type_to_string.c b/common/type_to_string.c
index 06c92aceb..de50e4096 100644
--- a/common/type_to_string.c
+++ b/common/type_to_string.c
@@ -5,6 +5,7 @@
 #include <common/type_to_string.h>
 #include <common/utils.h>
 #include <inttypes.h>
+#include <assert.h>
 
 /* We need at least one, and these are in CCAN so register it here. */
 REGISTER_TYPE_TO_HEXSTR(sha256);
@@ -20,6 +21,8 @@ char *type_to_string_(const tal_t *ctx,  const char *typename,
 	static size_t num_p;
 	static struct type_to_string **t = NULL;
 
+	assert(typename != NULL);
+
 	if (!t)
 		t = autodata_get(type_to_string, &num_p);
 
diff --git a/common/utils.c b/common/utils.c
index e46b9ef37..6011a417f 100644
--- a/common/utils.c
+++ b/common/utils.c
@@ -53,6 +53,9 @@ const char *tmpctx_any(void)
 	struct tmpctx *t = list_top(&tmpctxs, struct tmpctx, list);
 
 	if (t)
+	{
+		assert(t->file != NULL);
 		return tal_fmt(t, "%s:%u", t->file, t->line);
+	}
 	return NULL;
 }
diff --git a/lightningd/jsonrpc.c b/lightningd/jsonrpc.c
index 83a8aa47f..380f7ccaf 100644
--- a/lightningd/jsonrpc.c
+++ b/lightningd/jsonrpc.c
@@ -264,6 +264,7 @@ static void connection_complete_ok(struct json_connection *jcon,
 				   const struct json_result *result)
 {
 	assert(id != NULL);
+	assert(result != NULL);
 
 	/* This JSON is simple enough that we build manually */
 	json_done(jcon, cmd, take(tal_fmt(jcon,
diff --git a/lightningd/memdump.c b/lightningd/memdump.c
index 3b68c8e61..fba264e04 100644
--- a/lightningd/memdump.c
+++ b/lightningd/memdump.c
@@ -73,6 +73,8 @@ static int json_add_syminfo(void *data, uintptr_t pc UNUSED,
 	struct json_result *response = data;
 	char *str;
 
+	assert(filename != NULL);
+	assert(function != NULL);
 	str = tal_fmt(response, "%s:%u (%s)", filename, lineno, function);
 	json_add_string(response, NULL, str);
 	tal_free(str);
diff --git a/lightningd/opt_time.c b/lightningd/opt_time.c
index 95c5e090d..e191592b5 100644
--- a/lightningd/opt_time.c
+++ b/lightningd/opt_time.c
@@ -4,6 +4,7 @@
 #include <errno.h>
 #include <inttypes.h>
 #include <stdio.h>
+#include <assert.h>
 
 static bool match(const char *str, const char *abbrev, const char *full)
 {
@@ -26,6 +27,8 @@ char *opt_set_time(const char *arg, struct timerel *t)
 	char *endp;
 	unsigned long int l;
 
+	assert(arg != NULL);
+
 	/* This is how the manpage says to do it.  Yech. */
 	errno = 0;
 	l = strtol(arg, &endp, 0);
@@ -82,6 +85,8 @@ char *opt_set_timeabs(const char *arg, struct timeabs *t)
 {
 	long double d;
 
+	assert(arg != NULL);
+
 	if (sscanf(arg, "%Lf", &d) != 1)
 		return tal_fmt(NULL, "'%s' is not a time", arg);
 	t->ts.tv_sec = d;
diff --git a/lightningd/options.c b/lightningd/options.c
index d3932fcf2..fced4f3de 100644
--- a/lightningd/options.c
+++ b/lightningd/options.c
@@ -71,6 +71,8 @@ static char *opt_set_u32(const char *arg, u32 *u)
 	char *endp;
 	unsigned long l;
 
+	assert(arg != NULL);
+
 	/* This is how the manpage says to do it.  Yech. */
 	errno = 0;
 	l = strtoul(arg, &endp, 0);
@@ -87,6 +89,8 @@ static char *opt_set_u16(const char *arg, u16 *u)
 	char *endp;
 	unsigned long l;
 
+	assert(arg != NULL);
+
 	/* This is how the manpage says to do it.  Yech. */
 	errno = 0;
 	l = strtoul(arg, &endp, 0);
@@ -103,6 +107,8 @@ static char *opt_set_s32(const char *arg, s32 *u)
 	char *endp;
 	long l;
 
+	assert(arg != NULL);
+
 	/* This is how the manpage says to do it.  Yech. */
 	errno = 0;
 	l = strtol(arg, &endp, 0);
@@ -119,6 +125,8 @@ static char *opt_add_ipaddr(const char *arg, struct lightningd *ld)
 	size_t n = tal_count(ld->wireaddrs);
 	char const *err_msg;
 
+	assert(arg != NULL);
+
 	tal_resize(&ld->wireaddrs, n+1);
 
 	if (!parse_wireaddr(arg, &ld->wireaddrs[n], ld->portnum, &err_msg)) {
@@ -146,6 +154,8 @@ static void opt_show_u16(char buf[OPT_SHOW_LEN], const u16 *u)
 
 static char *opt_set_network(const char *arg, struct lightningd *ld)
 {
+	assert(arg != NULL);
+
 	ld->topology->bitcoind->chainparams = chainparams_for_network(arg);
 	if (!ld->topology->bitcoind->chainparams)
 		return tal_fmt(NULL, "Unknown network name '%s'", arg);
@@ -160,6 +170,8 @@ static void opt_show_network(char buf[OPT_SHOW_LEN],
 
 static char *opt_set_rgb(const char *arg, struct lightningd *ld)
 {
+	assert(arg != NULL);
+
 	ld->rgb = tal_free(ld->rgb);
 	/* BOLT #7:
 	 *
@@ -173,6 +185,8 @@ static char *opt_set_rgb(const char *arg, struct lightningd *ld)
 
 static char *opt_set_alias(const char *arg, struct lightningd *ld)
 {
+	assert(arg != NULL);
+
 	ld->alias = tal_free(ld->alias);
 	/* BOLT #7:
 	 *
@@ -298,6 +312,8 @@ static void config_register_opts(struct lightningd *ld)
 #if DEVELOPER
 static char *opt_set_hsm_seed(const char *arg, struct lightningd *ld)
 {
+	assert(arg != NULL);
+
 	ld->dev_hsm_seed = tal_hexdata(ld, arg, strlen(arg));
 	if (ld->dev_hsm_seed)
 		return NULL;
@@ -479,6 +495,7 @@ static void config_log_stderr_exit(const char *fmt, ...)
 		const char *arg = va_arg(ap, const char *);
 		const char *problem = va_arg(ap, const char *);
 
+		assert(arg != NULL);
 		msg = tal_fmt(NULL, "%s line %s: %.*s: %s",
 			      argv0, arg+strlen(arg)+1, len-2, arg+2, problem);
 	} else {
diff --git a/lightningd/pay.c b/lightningd/pay.c
index a10798b4a..ea13f9145 100644
--- a/lightningd/pay.c
+++ b/lightningd/pay.c
@@ -672,6 +672,7 @@ static void json_sendpay_on_resolve(const struct sendpay_result *r,
 				     r->onionreply, tal_len(r->onionreply));
 			json_object_end(data);
 
+			assert(r->details != NULL);
 			msg = tal_fmt(cmd,
 				      "failed: WIRE_PERMANENT_NODE_FAILURE "
 				      "(%s)",
@@ -700,6 +701,7 @@ static void json_sendpay_on_resolve(const struct sendpay_result *r,
 					     tal_len(fail->channel_update));
 			json_object_end(data);
 
+			assert(r->details != NULL);
 			msg = tal_fmt(cmd,
 				      "failed: %s (%s)",
 				      onion_type_name(fail->failcode),
diff --git a/lightningd/payalgo.c b/lightningd/payalgo.c
index c2aa3c9a2..83d5ca946 100644
--- a/lightningd/payalgo.c
+++ b/lightningd/payalgo.c
@@ -106,6 +106,7 @@ static void json_pay_failure(struct pay *pay,
 				     tal_len(fail->channel_update));
 		json_object_end(data);
 
+		assert(r->details != NULL);
 		msg = tal_fmt(pay,
 			      "failed: %s (%s)",
 			      onion_type_name(fail->failcode),
diff --git a/lightningd/peer_htlcs.c b/lightningd/peer_htlcs.c
index 1592f98e5..d0914304a 100644
--- a/lightningd/peer_htlcs.c
+++ b/lightningd/peer_htlcs.c
@@ -805,6 +805,7 @@ void onchain_failed_our_htlc(const struct channel *channel,
 	hout->failcode = WIRE_PERMANENT_CHANNEL_FAILURE;
 
 	if (!hout->in) {
+		assert(why != NULL);
 		char *localfail = tal_fmt(channel, "%s: %s",
 					  onion_type_name(WIRE_PERMANENT_CHANNEL_FAILURE),
 					  why);
diff --git a/lightningd/subd.c b/lightningd/subd.c
index 69e0a71e8..97d709b27 100644
--- a/lightningd/subd.c
+++ b/lightningd/subd.c
@@ -659,6 +659,8 @@ static struct subd *new_subd(struct lightningd *ld,
 	const char *debug_subd = NULL;
 	int disconnect_fd = -1;
 
+	assert(name != NULL);
+
 #if DEVELOPER
 	debug_subd = ld->dev_debug_subdaemon;
 	disconnect_fd = ld->dev_disconnect_fd;
diff --git a/test/test_state_coverage.c b/test/test_state_coverage.c
index 2713f03bb..29955ba3d 100644
--- a/test/test_state_coverage.c
+++ b/test/test_state_coverage.c
@@ -489,6 +489,7 @@ static unsigned int htlc_id_from_pkt(const Pkt *pkt)
 static Pkt *htlc_pkt(const tal_t *ctx, const char *prefix, unsigned int id)
 {
 	assert(id != -1);
+	assert(prefix != NULL);
 	return (Pkt *)tal_fmt(ctx, "%s: HTLC #%u", prefix, id);
 }
 
@@ -501,6 +502,7 @@ static unsigned int htlc_id_from_tx(const struct bitcoin_tx *tx)
 static struct bitcoin_tx *htlc_tx(const tal_t *ctx,
 				  const char *prefix, unsigned int id)
 {
+	assert(prefix != NULL);
 	return (struct bitcoin_tx *)tal_fmt(ctx, "%s HTLC #%u", prefix, id);
 }