diff --git a/include/internal/sizes.h b/include/internal/sizes.h
new file mode 100644
index 0000000000..fab5cbdec7
--- /dev/null
+++ b/include/internal/sizes.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#ifndef OSSL_INTERNAL_SIZES_H
+# define OSSL_INTERNAL_SIZES_H
+
+/*
+ * Max sizes used to allocate buffers with a fixed sizes, for example for
+ * stack allocations, structure fields, ...
+ */
+# define OSSL_MAX_NAME_SIZE           50 /* Algorithm name */
+# define OSSL_MAX_PROPQUERY_SIZE     256 /* Property query strings */
+
+#endif
diff --git a/providers/implementations/asymciphers/rsa_enc.c b/providers/implementations/asymciphers/rsa_enc.c
index 53fc6de265..77f807e7ef 100644
--- a/providers/implementations/asymciphers/rsa_enc.c
+++ b/providers/implementations/asymciphers/rsa_enc.c
@@ -17,6 +17,7 @@
 /* Just for SSL_MAX_MASTER_KEY_LENGTH */
 #include <openssl/ssl.h>
 #include "internal/constant_time.h"
+#include "internal/sizes.h"
 #include "crypto/rsa.h"
 #include "prov/providercommonerr.h"
 #include "prov/provider_ctx.h"
@@ -322,8 +323,8 @@ static int rsa_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
 {
     PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
     const OSSL_PARAM *p;
-    /* Should be big enough */
-    char mdname[80], mdprops[80] = { '\0' };
+    char mdname[OSSL_MAX_NAME_SIZE];
+    char mdprops[OSSL_MAX_PROPQUERY_SIZE] = { '\0' };
     char *str = mdname;
     int pad_mode;
 
diff --git a/providers/implementations/signature/dsa.c b/providers/implementations/signature/dsa.c
index c656a45fd7..9892e6d5e4 100644
--- a/providers/implementations/signature/dsa.c
+++ b/providers/implementations/signature/dsa.c
@@ -13,6 +13,7 @@
 #include <openssl/dsa.h>
 #include <openssl/params.h>
 #include <openssl/evp.h>
+#include "internal/sizes.h"
 #include "prov/implementations.h"
 #include "prov/provider_ctx.h"
 #include "crypto/dsa.h"
@@ -49,8 +50,7 @@ typedef struct {
     OPENSSL_CTX *libctx;
     DSA *dsa;
     size_t mdsize;
-    /* Should be big enough */
-    char mdname[80];
+    char mdname[OSSL_MAX_NAME_SIZE];
     EVP_MD *md;
     EVP_MD_CTX *mdctx;
 } PROV_DSA_CTX;