diff --git a/common/json.c b/common/json.c
index 2db012c2d..1383b877d 100644
--- a/common/json.c
+++ b/common/json.c
@@ -66,7 +66,7 @@ bool json_to_u64(const char *buffer, const jsmntok_t *tok,
 	return true;
 }
 
-bool json_tok_double(const char *buffer, const jsmntok_t *tok, double *num)
+bool json_to_double(const char *buffer, const jsmntok_t *tok, double *num)
 {
 	char *end;
 
@@ -78,7 +78,7 @@ bool json_tok_double(const char *buffer, const jsmntok_t *tok, double *num)
 
 bool json_tok_percent(const char *buffer, const jsmntok_t *tok, double *num)
 {
-	if (!json_tok_double(buffer, tok, num))
+	if (!json_to_double(buffer, tok, num))
 		return false;
 
 	/* Ensure it is in the range [0.0, 100.0] */
diff --git a/common/json.h b/common/json.h
index 1cf45d0ba..fc175dd5d 100644
--- a/common/json.h
+++ b/common/json.h
@@ -33,7 +33,7 @@ bool json_to_u64(const char *buffer, const jsmntok_t *tok,
 		 uint64_t *num);
 
 /* Extract double from this (must be a number literal) */
-bool json_tok_double(const char *buffer, const jsmntok_t *tok, double *num);
+bool json_to_double(const char *buffer, const jsmntok_t *tok, double *num);
 
 /* Extract satoshis from this (may be a string, or a decimal number literal) */
 bool json_tok_bitcoin_amount(const char *buffer, const jsmntok_t *tok,
diff --git a/lightningd/bitcoind.c b/lightningd/bitcoind.c
index 6d3781c7a..95a6e3b9d 100644
--- a/lightningd/bitcoind.c
+++ b/lightningd/bitcoind.c
@@ -303,7 +303,7 @@ static bool extract_feerate(struct bitcoin_cli *bcli,
 	if (!feeratetok)
 		return false;
 
-	return json_tok_double(output, feeratetok, feerate);
+	return json_to_double(output, feeratetok, feerate);
 }
 
 struct estimatefee {
diff --git a/lightningd/gossip_control.c b/lightningd/gossip_control.c
index becf3bece..586952d22 100644
--- a/lightningd/gossip_control.c
+++ b/lightningd/gossip_control.c
@@ -277,34 +277,34 @@ static void json_getroute(struct command *cmd, const char *buffer, const jsmntok
 	const jsmntok_t *seedtok;
 	u64 *msatoshi;
 	unsigned *cltv;
-	double riskfactor;
+	double *riskfactor;
 	/* Higher fuzz means that some high-fee paths can be discounted
 	 * for an even larger value, increasing the scope for route
 	 * randomization (the higher-fee paths become more likely to
 	 * be selected) at the cost of increasing the probability of
 	 * selecting the higher-fee paths. */
-	double fuzz;
+	double *fuzz;
 	struct siphash_seed seed;
 
 	if (!param(cmd, buffer, params,
 		   p_req("id", json_tok_pubkey, &destination),
 		   p_req_tal("msatoshi", json_tok_u64, &msatoshi),
-		   p_req("riskfactor", json_tok_double, &riskfactor),
+		   p_req_tal("riskfactor", json_tok_double, &riskfactor),
 		   p_opt_def_tal("cltv", json_tok_number, &cltv, 9),
 		   p_opt_def("fromid", json_tok_pubkey, &source, ld->id),
-		   p_opt_def("fuzzpercent", json_tok_double, &fuzz, 75.0),
 		   p_opt_tal("seed", json_tok_tok, &seedtok),
+		   p_opt_def_tal("fuzzpercent", json_tok_double, &fuzz, 75.0),
 		   NULL))
 		return;
 
-	if (!(0.0 <= fuzz && fuzz <= 100.0)) {
+	if (!(0.0 <= *fuzz && *fuzz <= 100.0)) {
 		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 			     "fuzz must be in range 0.0 <= %f <= 100.0",
-			     fuzz);
+			     *fuzz);
 		return;
 	}
 	/* Convert from percentage */
-	fuzz = fuzz / 100.0;
+	*fuzz = *fuzz / 100.0;
 
 	if (seedtok) {
 		if (seedtok->end - seedtok->start > sizeof(seed))
@@ -317,7 +317,9 @@ static void json_getroute(struct command *cmd, const char *buffer, const jsmntok
 	} else
 		randombytes_buf(&seed, sizeof(seed));
 
-	u8 *req = towire_gossip_getroute_request(cmd, &source, &destination, *msatoshi, riskfactor*1000, *cltv, &fuzz, &seed);
+	u8 *req = towire_gossip_getroute_request(cmd, &source, &destination,
+						 *msatoshi, *riskfactor * 1000,
+						 *cltv, fuzz, &seed);
 	subd_req(ld->gossip, ld->gossip, req, -1, 0, json_getroute_reply, cmd);
 	command_still_pending(cmd);
 }
diff --git a/lightningd/json.c b/lightningd/json.c
index b3792a431..2488c4a95 100644
--- a/lightningd/json.c
+++ b/lightningd/json.c
@@ -91,6 +91,20 @@ void json_add_txid(struct json_result *result, const char *fieldname,
 	json_add_string(result, fieldname, hex);
 }
 
+bool json_tok_double(struct command *cmd, const char *name,
+		     const char *buffer, const jsmntok_t *tok,
+		     double **num)
+{
+	*num = tal(cmd, double);
+	if (!json_to_double(buffer, tok, *num)) {
+		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			     "'%s' should be a double, not '%.*s'",
+			     name, tok->end - tok->start, buffer + tok->start);
+		return false;
+	}
+	return true;
+}
+
 bool json_tok_number(struct command *cmd, const char *name,
 		     const char *buffer, const jsmntok_t *tok,
 		     unsigned int **num)
diff --git a/lightningd/json.h b/lightningd/json.h
index 7dc26f199..fc4acee44 100644
--- a/lightningd/json.h
+++ b/lightningd/json.h
@@ -41,6 +41,11 @@ void json_add_pubkey(struct json_result *response,
 void json_add_txid(struct json_result *result, const char *fieldname,
 		   const struct bitcoin_txid *txid);
 
+/* Extract double from this (must be a number literal) */
+bool json_tok_double(struct command *cmd, const char *name,
+		     const char *buffer, const jsmntok_t *tok,
+		     double **num);
+
 /* Extract number from this (may be a string, or a number literal) */
 bool json_tok_number(struct command *cmd, const char *name,
 		     const char *buffer, const jsmntok_t *tok,
diff --git a/lightningd/param.c b/lightningd/param.c
index 7f7aa1e7e..4e9c12f37 100644
--- a/lightningd/param.c
+++ b/lightningd/param.c
@@ -51,7 +51,6 @@ struct fail_format {
 
 static struct fail_format fail_formats[] = {
 	{json_tok_bool, "'%s' should be 'true' or 'false', not '%.*s'"},
-	{json_tok_double, "'%s' should be a double, not '%.*s'"},
 	{json_tok_percent,
 	 "'%s' should be a double in range [0.0, 100.0], not '%.*s'"},
 	{json_tok_newaddr, "'%s' should be 'bech32' or 'p2sh-segwit', not '%.*s'"},
diff --git a/lightningd/payalgo.c b/lightningd/payalgo.c
index f9809cd74..cb0557d9c 100644
--- a/lightningd/payalgo.c
+++ b/lightningd/payalgo.c
@@ -600,7 +600,7 @@ static void json_pay(struct command *cmd,
 		     const char *buffer, const jsmntok_t *params)
 {
 	const jsmntok_t *bolt11tok, *desctok;
-	double riskfactor;
+	double *riskfactor;
 	double maxfeepercent;
 	u64 *msatoshi;
 	struct pay *pay = tal(cmd, struct pay);
@@ -612,9 +612,9 @@ static void json_pay(struct command *cmd,
 
 	if (!param(cmd, buffer, params,
 		   p_req_tal("bolt11", json_tok_tok, &bolt11tok),
-		   p_opt_tal("description", json_tok_tok, &desctok),
 		   p_opt_tal("msatoshi", json_tok_u64, &msatoshi),
-		   p_opt_def("riskfactor", json_tok_double, &riskfactor, 1.0),
+		   p_opt_tal("description", json_tok_tok, &desctok),
+		   p_opt_def_tal("riskfactor", json_tok_double, &riskfactor, 1.0),
 		   p_opt_def("maxfeepercent", json_tok_percent, &maxfeepercent, 0.5),
 		   p_opt_def_tal("retry_for", json_tok_number, &retryfor, 60),
 		   p_opt_def_tal("maxdelay", json_tok_number, &maxdelay,
@@ -661,7 +661,7 @@ static void json_pay(struct command *cmd,
 		}
 	}
 	pay->msatoshi = *msatoshi;
-	pay->riskfactor = riskfactor * 1000;
+	pay->riskfactor = *riskfactor * 1000;
 	pay->maxfeepercent = maxfeepercent;
 
 	if (*maxdelay < pay->min_final_cltv_expiry) {
diff --git a/lightningd/test/run-param.c b/lightningd/test/run-param.c
index c7b1c8ca5..7b9f63e06 100644
--- a/lightningd/test/run-param.c
+++ b/lightningd/test/run-param.c
@@ -137,10 +137,10 @@ struct sanity buffers[] = {
 static void stest(const struct json *j, struct sanity *b)
 {
 	u64 *ival;
-	double dval;
+	double *dval;
 	if (!param(cmd, j->buffer, j->toks,
 		   p_req_tal("u64", json_tok_u64, &ival),
-		   p_req("double", json_tok_double, &dval), NULL)) {
+		   p_req_tal("double", json_tok_double, &dval), NULL)) {
 		assert(check_fail());
 		assert(b->failed == true);
 		if (!strstr(fail_msg, b->fail_str)) {
@@ -151,7 +151,7 @@ static void stest(const struct json *j, struct sanity *b)
 		assert(!check_fail());
 		assert(b->failed == false);
 		assert(*ival == 42);
-		assert(dval > 3.1499 && b->dval < 3.1501);
+		assert(*dval > 3.1499 && b->dval < 3.1501);
 	}
 }
 
@@ -204,10 +204,10 @@ static void dup_names(void)
 			   "{ 'u64' : '42', 'u64' : '43', 'double' : '3.15' }");
 
 	u64 *i;
-	double d;
+	double *d;
 	assert(!param(cmd, j->buffer, j->toks,
 		      p_req_tal("u64", json_tok_u64, &i),
-		      p_req("double", json_tok_double, &d), NULL));
+		      p_req_tal("double", json_tok_double, &d), NULL));
 }
 
 static void null_params(void)
@@ -259,28 +259,28 @@ static void bad_programmer(void)
 {
 	u64 *ival;
 	u64 *ival2;
-	double dval;
+	double *dval;
 	struct json *j = json_parse(cmd, "[ '25', '546', '26' ]");
 
 	/* check for repeated names */
 	assert(!param(cmd, j->buffer, j->toks,
 		      p_req_tal("repeat", json_tok_u64, &ival),
-		      p_req("double", json_tok_double, &dval),
+		      p_req_tal("double", json_tok_double, &dval),
 		      p_req_tal("repeat", json_tok_u64, &ival2), NULL));
 	assert(check_fail());
 	assert(strstr(fail_msg, "developer error"));
 
 	assert(!param(cmd, j->buffer, j->toks,
 		      p_req_tal("repeat", json_tok_u64, &ival),
-		      p_req("double", json_tok_double, &dval),
+		      p_req_tal("double", json_tok_double, &dval),
 		      p_req_tal("repeat", json_tok_u64, &ival), NULL));
 	assert(check_fail());
 	assert(strstr(fail_msg, "developer error"));
 
 	assert(!param(cmd, j->buffer, j->toks,
 		      p_req_tal("u64", json_tok_u64, &ival),
-		      p_req("repeat", json_tok_double, &dval),
-		      p_req("repeat", json_tok_double, &dval), NULL));
+		      p_req_tal("repeat", json_tok_double, &dval),
+		      p_req_tal("repeat", json_tok_double, &dval), NULL));
 	assert(check_fail());
 	assert(strstr(fail_msg, "developer error"));
 
@@ -299,12 +299,12 @@ static void bad_programmer(void)
 	/* Add required param after optional */
 	j = json_parse(cmd, "[ '25', '546', '26', '1.1' ]");
 	unsigned int *msatoshi;
-	double riskfactor;
+	double *riskfactor;
 	assert(!param(cmd, j->buffer, j->toks,
 		      p_req_tal("u64", json_tok_u64, &ival),
-		      p_req("double", json_tok_double, &dval),
+		      p_req_tal("double", json_tok_double, &dval),
 		      p_opt_def_tal("msatoshi", json_tok_number, &msatoshi, 100),
-		      p_req("riskfactor", json_tok_double, &riskfactor), NULL));
+		      p_req_tal("riskfactor", json_tok_double, &riskfactor), NULL));
 	assert(*msatoshi);
 	assert(*msatoshi == 100);
 	assert(check_fail());