diff --git a/crypto/pem/pem_lib.c b/crypto/pem/pem_lib.c
index afa39d7..8f89096 100644
--- a/crypto/pem/pem_lib.c
+++ b/crypto/pem/pem_lib.c
@@ -764,13 +764,13 @@
 
 int PEM_def_callback(char *buf, int size, int rwflag, void *userdata)
 {
-    if (!buf || !userdata) {
+    if (!buf || !userdata || size < 0) {
         return 0;
     }
     size_t len = strlen((char *)userdata);
     if (len >= (size_t)size) {
         return 0;
     }
-    strcpy(buf, (char *)userdata);
+    BUF_strlcpy(buf, userdata, (size_t)size);
     return len;
 }
diff --git a/crypto/x509/by_dir.c b/crypto/x509/by_dir.c
index d72f9ec..018c5d1 100644
--- a/crypto/x509/by_dir.c
+++ b/crypto/x509/by_dir.c
@@ -235,8 +235,7 @@
                 by_dir_entry_free(ent);
                 return 0;
             }
-            strncpy(ent->dir, ss, len);
-            ent->dir[len] = '\0';
+            BUF_strlcpy(ent->dir, ss, len + 1);
             if (!sk_BY_DIR_ENTRY_push(ctx->dirs, ent)) {
                 by_dir_entry_free(ent);
                 return 0;
diff --git a/crypto/x509/x509_obj.c b/crypto/x509/x509_obj.c
index 33eafc4..f9f0308 100644
--- a/crypto/x509/x509_obj.c
+++ b/crypto/x509/x509_obj.c
@@ -102,8 +102,7 @@
             buf = b->data;
             OPENSSL_free(b);
         }
-        strncpy(buf, "NO X509_NAME", len);
-        buf[len - 1] = '\0';
+        BUF_strlcpy(buf, "NO X509_NAME", len);
         return buf;
     }
 
diff --git a/crypto/x509v3/v3_alt.c b/crypto/x509v3/v3_alt.c
index 6280651..b78a410 100644
--- a/crypto/x509v3/v3_alt.c
+++ b/crypto/x509v3/v3_alt.c
@@ -166,9 +166,9 @@
             for (i = 0; i < 8; i++) {
                 BIO_snprintf(htmp, sizeof htmp, "%X", p[0] << 8 | p[1]);
                 p += 2;
-                strcat(oline, htmp);
+                BUF_strlcat(oline, htmp, sizeof(oline));
                 if (i != 7)
-                    strcat(oline, ":");
+                    BUF_strlcat(oline, ":", sizeof(oline));
             }
         } else {
             if (!X509V3_add_value("IP Address", "<invalid>", &ret))
@@ -588,8 +588,7 @@
     objtmp = OPENSSL_malloc(objlen + 1);
     if (objtmp == NULL)
         return 0;
-    strncpy(objtmp, value, objlen);
-    objtmp[objlen] = 0;
+    BUF_strlcpy(objtmp, value, objlen + 1);
     gen->d.otherName->type_id = OBJ_txt2obj(objtmp, 0);
     OPENSSL_free(objtmp);
     if (!gen->d.otherName->type_id)
diff --git a/crypto/x509v3/v3_info.c b/crypto/x509v3/v3_info.c
index 40f451f..ff96489 100644
--- a/crypto/x509v3/v3_info.c
+++ b/crypto/x509v3/v3_info.c
@@ -192,8 +192,7 @@
             OPENSSL_PUT_ERROR(X509V3, ERR_R_MALLOC_FAILURE);
             goto err;
         }
-        strncpy(objtmp, cnf->name, objlen);
-        objtmp[objlen] = 0;
+        BUF_strlcpy(objtmp, cnf->name, objlen + 1);
         acc->method = OBJ_txt2obj(objtmp, 0);
         if (!acc->method) {
             OPENSSL_PUT_ERROR(X509V3, X509V3_R_BAD_OBJECT);