diff --git a/include/mbedtls/config_adjust_legacy_from_psa.h b/include/mbedtls/config_adjust_legacy_from_psa.h
index 8d864ab6d..471ba181b 100644
--- a/include/mbedtls/config_adjust_legacy_from_psa.h
+++ b/include/mbedtls/config_adjust_legacy_from_psa.h
@@ -67,6 +67,10 @@
 
 #if defined(PSA_WANT_ALG_HKDF)
 #if !defined(MBEDTLS_PSA_ACCEL_ALG_HKDF)
+/*
+ * The PSA implementation has its own implementation of HKDF, separate from
+ * hkdf.c. No need to enable MBEDTLS_HKDF_C here.
+ */
 #define MBEDTLS_PSA_BUILTIN_ALG_HMAC 1
 #define MBEDTLS_PSA_BUILTIN_ALG_HKDF 1
 #endif /* !MBEDTLS_PSA_ACCEL_ALG_HKDF */
@@ -74,6 +78,10 @@
 
 #if defined(PSA_WANT_ALG_HKDF_EXTRACT)
 #if !defined(MBEDTLS_PSA_ACCEL_ALG_HKDF_EXTRACT)
+/*
+ * The PSA implementation has its own implementation of HKDF, separate from
+ * hkdf.c. No need to enable MBEDTLS_HKDF_C here.
+ */
 #define MBEDTLS_PSA_BUILTIN_ALG_HMAC 1
 #define MBEDTLS_PSA_BUILTIN_ALG_HKDF_EXTRACT 1
 #endif /* !MBEDTLS_PSA_ACCEL_ALG_HKDF_EXTRACT */
@@ -81,6 +89,10 @@
 
 #if defined(PSA_WANT_ALG_HKDF_EXPAND)
 #if !defined(MBEDTLS_PSA_ACCEL_ALG_HKDF_EXPAND)
+/*
+ * The PSA implementation has its own implementation of HKDF, separate from
+ * hkdf.c. No need to enable MBEDTLS_HKDF_C here.
+ */
 #define MBEDTLS_PSA_BUILTIN_ALG_HMAC 1
 #define MBEDTLS_PSA_BUILTIN_ALG_HKDF_EXPAND 1
 #endif /* !MBEDTLS_PSA_ACCEL_ALG_HKDF_EXPAND */