diff --git a/include/mbedtls/ecdsa.h b/include/mbedtls/ecdsa.h
index 119ee26463..cbe4679d1d 100644
--- a/include/mbedtls/ecdsa.h
+++ b/include/mbedtls/ecdsa.h
@@ -207,7 +207,7 @@ int mbedtls_ecdsa_sign_det_ext(mbedtls_ecp_group *grp, mbedtls_mpi *r,
                                mbedtls_mpi *s, const mbedtls_mpi *d,
                                const unsigned char *buf, size_t blen,
                                mbedtls_md_type_t md_alg,
-                               int (*f_rng_blind)(void *, unsigned char *, size_t),
+                               mbedtls_f_rng_t *f_rng_blind,
                                void *p_rng_blind);
 #endif /* MBEDTLS_ECDSA_DETERMINISTIC */
 
@@ -273,7 +273,7 @@ int mbedtls_ecdsa_sign_restartable(
     const unsigned char *buf, size_t blen,
     mbedtls_f_rng_t *f_rng,
     void *p_rng,
-    int (*f_rng_blind)(void *, unsigned char *, size_t),
+    mbedtls_f_rng_t *f_rng_blind,
     void *p_rng_blind,
     mbedtls_ecdsa_restart_ctx *rs_ctx);
 
@@ -334,7 +334,7 @@ int mbedtls_ecdsa_sign_det_restartable(
     mbedtls_mpi *r, mbedtls_mpi *s,
     const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
     mbedtls_md_type_t md_alg,
-    int (*f_rng_blind)(void *, unsigned char *, size_t),
+    mbedtls_f_rng_t *f_rng_blind,
     void *p_rng_blind,
     mbedtls_ecdsa_restart_ctx *rs_ctx);