diff --git a/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h b/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
index 597544895..b504f20d9 100644
--- a/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
+++ b/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
@@ -33,6 +33,7 @@
 #endif // DISABLE_CC310
 
 #define MBEDTLS_ECDH_C
+#define MBEDTLS_ECDSA_C
 
 #if defined(__ICCARM__)
     _Pragma("diag_suppress=Pe549")