diff --git a/tests/net/lib/lwm2m/content_json/prj.conf b/tests/net/lib/lwm2m/content_json/prj.conf
index 3f2cd3e60f249e8..7b7907492658513 100644
--- a/tests/net/lib/lwm2m/content_json/prj.conf
+++ b/tests/net/lib/lwm2m/content_json/prj.conf
@@ -9,3 +9,6 @@ CONFIG_LWM2M=y
 CONFIG_LWM2M_COAP_MAX_MSG_SIZE=512
 CONFIG_LWM2M_RW_JSON_SUPPORT=y
 CONFIG_JSON_LIBRARY=y
+
+CONFIG_PICOLIBC=y
+CONFIG_PICOLIBC_IO_FLOAT=y
diff --git a/tests/net/lib/lwm2m/content_plain_text/prj.conf b/tests/net/lib/lwm2m/content_plain_text/prj.conf
index 6041addad83722f..c0c829d5c0d12d0 100644
--- a/tests/net/lib/lwm2m/content_plain_text/prj.conf
+++ b/tests/net/lib/lwm2m/content_plain_text/prj.conf
@@ -6,3 +6,6 @@ CONFIG_ZTEST_NEW_API=y
 CONFIG_ENTROPY_GENERATOR=y
 CONFIG_TEST_RANDOM_GENERATOR=y
 CONFIG_LWM2M=y
+
+CONFIG_PICOLIBC=y
+CONFIG_PICOLIBC_IO_FLOAT=y