diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 55fca55..719ffb7 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -162,7 +162,8 @@
 #error "MBEDTLS_PKCS12_C defined, but not all prerequisites"
 #endif
 
-#if defined(MBEDTLS_PKCS1_V21) && !defined(MBEDTLS_MD_C)
+#if defined(MBEDTLS_PKCS1_V21) && \
+    !( defined(MBEDTLS_MD_C) || defined(MBEDTLS_PSA_CRYPTO_C) )
 #error "MBEDTLS_PKCS1_V21 defined, but not all prerequisites"
 #endif
 
diff --git a/include/mbedtls/config_psa.h b/include/mbedtls/config_psa.h
index 2e9e451..fbfcdc3 100644
--- a/include/mbedtls/config_psa.h
+++ b/include/mbedtls/config_psa.h
@@ -158,7 +158,6 @@
 #define MBEDTLS_BIGNUM_C
 #define MBEDTLS_OID_C
 #define MBEDTLS_PKCS1_V21
-#define MBEDTLS_MD_C
 #endif /* !MBEDTLS_PSA_ACCEL_ALG_RSA_OAEP */
 #endif /* PSA_WANT_ALG_RSA_OAEP */
 
@@ -189,7 +188,6 @@
 #define MBEDTLS_BIGNUM_C
 #define MBEDTLS_OID_C
 #define MBEDTLS_PKCS1_V21
-#define MBEDTLS_MD_C
 #endif /* !MBEDTLS_PSA_ACCEL_ALG_RSA_PSS */
 #endif /* PSA_WANT_ALG_RSA_PSS */
 
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index e96a797..d7662ef 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -1141,7 +1141,10 @@
  *
  * Enable support for PKCS#1 v2.1 encoding.
  *
- * Requires: MBEDTLS_MD_C, MBEDTLS_RSA_C
+ * Requires: MBEDTLS_RSA_C and (MBEDTLS_MD_C or MBEDTLS_PSA_CRYPTO_C).
+ *
+ * \warning If building without MBEDTLS_MD_C, you must call psa_crypto_init()
+ * before doing any PKCS#1 v2.1 operation.
  *
  * This enables support for RSAES-OAEP and RSASSA-PSS operations.
  */