diff --git a/src/options.cpp b/src/options.cpp
index 84b2a7b1..5450dbf2 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -376,19 +376,21 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
             }
             else
             if (optvallen_ == CURVE_KEYSIZE_Z85 + 1) {
-                zmq_z85_decode (curve_public_key, (char *) optval_);
-                mechanism = ZMQ_CURVE;
-                return 0;
+                if (zmq_z85_decode (curve_public_key, (char *) optval_)) {
+                    mechanism = ZMQ_CURVE;
+                    return 0;
+                }
             }
             else
             //  Deprecated, not symmetrical with zmq_getsockopt
             if (optvallen_ == CURVE_KEYSIZE_Z85) {
-                char z85_key [41];
+                char z85_key [CURVE_KEYSIZE_Z85 + 1];
                 memcpy (z85_key, (char *) optval_, CURVE_KEYSIZE_Z85);
                 z85_key [CURVE_KEYSIZE_Z85] = 0;
-                zmq_z85_decode (curve_public_key, z85_key);
-                mechanism = ZMQ_CURVE;
-                return 0;
+                if (zmq_z85_decode (curve_public_key, z85_key)) {
+                    mechanism = ZMQ_CURVE;
+                    return 0;
+                }
             }
             break;
 
@@ -400,19 +402,21 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
             }
             else
             if (optvallen_ == CURVE_KEYSIZE_Z85 + 1) {
-                zmq_z85_decode (curve_secret_key, (char *) optval_);
-                mechanism = ZMQ_CURVE;
-                return 0;
+                if (zmq_z85_decode (curve_secret_key, (char *) optval_)) {
+                    mechanism = ZMQ_CURVE;
+                    return 0;
+                }
             }
             else
             //  Deprecated, not symmetrical with zmq_getsockopt
             if (optvallen_ == CURVE_KEYSIZE_Z85) {
-                char z85_key [41];
+                char z85_key [CURVE_KEYSIZE_Z85 + 1];
                 memcpy (z85_key, (char *) optval_, CURVE_KEYSIZE_Z85);
                 z85_key [CURVE_KEYSIZE_Z85] = 0;
-                zmq_z85_decode (curve_secret_key, z85_key);
-                mechanism = ZMQ_CURVE;
-                return 0;
+                if (zmq_z85_decode (curve_secret_key, z85_key)) {
+                    mechanism = ZMQ_CURVE;
+                    return 0;
+                }
             }
             break;
 
@@ -425,21 +429,23 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
             }
             else
             if (optvallen_ == CURVE_KEYSIZE_Z85 + 1) {
-                zmq_z85_decode (curve_server_key, (char *) optval_);
-                mechanism = ZMQ_CURVE;
-                as_server = 0;
-                return 0;
+                if (zmq_z85_decode (curve_server_key, (char *) optval_)) {
+                    mechanism = ZMQ_CURVE;
+                    as_server = 0;
+                    return 0;
+                }
             }
             else
             //  Deprecated, not symmetrical with zmq_getsockopt
             if (optvallen_ == CURVE_KEYSIZE_Z85) {
-                char z85_key [41];
+                char z85_key [CURVE_KEYSIZE_Z85 + 1];
                 memcpy (z85_key, (char *) optval_, CURVE_KEYSIZE_Z85);
                 z85_key [CURVE_KEYSIZE_Z85] = 0;
-                zmq_z85_decode (curve_server_key, z85_key);
-                mechanism = ZMQ_CURVE;
-                as_server = 0;
-                return 0;
+                if (zmq_z85_decode (curve_server_key, z85_key)) {
+                    mechanism = ZMQ_CURVE;
+                    as_server = 0;
+                    return 0;
+                }
             }
             break;
 #       endif
diff --git a/tests/test_security_curve.cpp b/tests/test_security_curve.cpp
index af3925ab..75ca8466 100644
--- a/tests/test_security_curve.cpp
+++ b/tests/test_security_curve.cpp
@@ -217,7 +217,22 @@ int main (void)
     assert (rc == 0);
     expect_bounce_fail (server, client);
     close_zero_linger (client);
-    
+
+    //  Check return codes for invalid buffer sizes
+    client = zmq_socket (ctx, ZMQ_DEALER);
+    assert (client);
+    errno = 0;
+    rc = zmq_setsockopt (client, ZMQ_CURVE_SERVERKEY, server_public, 123);
+    assert (rc == -1 && errno == EINVAL);
+    errno = 0;
+    rc = zmq_setsockopt (client, ZMQ_CURVE_PUBLICKEY, client_public, 123);
+    assert (rc == -1 && errno == EINVAL);
+    errno = 0;
+    rc = zmq_setsockopt (client, ZMQ_CURVE_SECRETKEY, client_secret, 123);
+    assert (rc == -1 && errno == EINVAL);
+    rc = zmq_close (client);
+    assert (rc == 0);
+
     //  Shutdown
     rc = zmq_close (server);
     assert (rc == 0);