diff --git a/targets/esp32.json b/targets/esp32.json
index 897ae33a..3559e892 100644
--- a/targets/esp32.json
+++ b/targets/esp32.json
@@ -9,6 +9,7 @@
 		"-mcpu=esp32"
 	],
 	"rtlib": "compiler-rt",
+	"libc": "picolibc",
 	"linkerscript": "targets/esp32.ld",
 	"extra-files": [
 		"src/device/esp/esp32.S",
diff --git a/targets/esp8266.json b/targets/esp8266.json
index 593d0769..e1304d24 100644
--- a/targets/esp8266.json
+++ b/targets/esp8266.json
@@ -9,6 +9,7 @@
 		"-mcpu=esp8266"
 	],
 	"rtlib": "compiler-rt",
+	"libc": "picolibc",
 	"linkerscript": "targets/esp8266.ld",
 	"extra-files": [
 		"src/device/esp/esp8266.S",