diff --git a/subsys/net/lib/lwm2m/lwm2m_engine.c b/subsys/net/lib/lwm2m/lwm2m_engine.c
index cad4c5a1697..4431e71507d 100644
--- a/subsys/net/lib/lwm2m/lwm2m_engine.c
+++ b/subsys/net/lib/lwm2m/lwm2m_engine.c
@@ -4326,7 +4326,7 @@ static int generate_notify_message(struct lwm2m_ctx *ctx,
 		obs->path.level,
 		log_strdup(sprint_token(obs->token, obs->tkl)),
 		log_strdup(lwm2m_sprint_ip_addr(&ctx->remote_addr)),
-		k_uptime_get());
+		(long long)k_uptime_get());
 
 	obj_inst = get_engine_obj_inst(obs->path.obj_id,
 				       obs->path.obj_inst_id);
diff --git a/subsys/net/lib/lwm2m/lwm2m_util.c b/subsys/net/lib/lwm2m/lwm2m_util.c
index 008c6bbe307..1df92811ca9 100644
--- a/subsys/net/lib/lwm2m/lwm2m_util.c
+++ b/subsys/net/lib/lwm2m/lwm2m_util.c
@@ -8,6 +8,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <ctype.h>
+#include <inttypes.h>
 #include "lwm2m_util.h"
 
 #define SHIFT_LEFT(v, o, m) (((v) << (o)) & (m))
@@ -378,7 +379,8 @@ int lwm2m_ftoa(double *input, char *out, size_t outlen, int8_t dec_limit)
 	int64_t val1 = (int64_t)*input;
 	int64_t val2 = (*input - (int64_t)*input) * PRECISION64;
 
-	len = snprintk(buf, sizeof(buf), "%0*lld", PRECISION64_LEN, llabs(val2));
+	len = snprintk(buf, sizeof(buf), "%0*lld", PRECISION64_LEN,
+		       (long long)llabs(val2));
 	if (len != PRECISION64_LEN) {
 		strcpy(buf, "0");
 	} else {
@@ -418,5 +420,5 @@ int lwm2m_ftoa(double *input, char *out, size_t outlen, int8_t dec_limit)
 
 	return snprintk(out, outlen, "%s%lld.%s",
 			/* handle negative val2 when val1 is 0 */
-			(val1 == 0 && val2 < 0) ? "-" : "", val1, buf);
+			(val1 == 0 && val2 < 0) ? "-" : "", (long long)val1, buf);
 }