diff --git a/ChangeLog b/ChangeLog
index ac0e32a..03c8568 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -32,6 +32,10 @@
    * Fix documentation and implementation missmatch for function arguments of
      mbedtls_gcm_finish(). Found by cmiatpaar. #602
    * Guarantee that P>Q at RSA key generation. Found by inestlerode. #558
+   * Fix missing return code check after call to mbedtls_md_setup() that could
+     result in usage of invalid md_ctx in mbedtls_rsa_rsaes_oaep_encrypt(),
+     mbedtls_rsa_rsaes_oaep_decrypt(), mbedtls_rsa_rsassa_pss_sign() and
+     mbedtls_rsa_rsassa_pss_verify_ext(). Fixed by Brian J. Murray.
 
 = mbed TLS 2.1.5 branch released 2016-06-28
 
diff --git a/library/rsa.c b/library/rsa.c
index 76e35de..e831875 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -551,7 +551,11 @@
     memcpy( p, input, ilen );
 
     mbedtls_md_init( &md_ctx );
-    mbedtls_md_setup( &md_ctx, md_info, 0 );
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
+    {
+        mbedtls_md_free( &md_ctx );
+        return( ret );
+    }
 
     // maskedDB: Apply dbMask to DB
     //
@@ -726,7 +730,12 @@
      * Unmask data and generate lHash
      */
     mbedtls_md_init( &md_ctx );
-    mbedtls_md_setup( &md_ctx, md_info, 0 );
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
+    {
+        mbedtls_md_free( &md_ctx );
+        return( ret );
+    }
+
 
     /* Generate lHash */
     mbedtls_md( md_info, label, label_len, lhash );
@@ -972,7 +981,11 @@
     p += slen;
 
     mbedtls_md_init( &md_ctx );
-    mbedtls_md_setup( &md_ctx, md_info, 0 );
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
+    {
+        mbedtls_md_free( &md_ctx );
+        return( ret );
+    }
 
     // Generate H = Hash( M' )
     //
@@ -1245,7 +1258,11 @@
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     mbedtls_md_init( &md_ctx );
-    mbedtls_md_setup( &md_ctx, md_info, 0 );
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
+    {
+        mbedtls_md_free( &md_ctx );
+        return( ret );
+    }
 
     mgf_mask( p, siglen - hlen - 1, p + siglen - hlen - 1, hlen, &md_ctx );