diff --git a/source/pdo_sqlsrv/pdo_stmt.cpp b/source/pdo_sqlsrv/pdo_stmt.cpp
index 59de9c90..7edb17dc 100644
--- a/source/pdo_sqlsrv/pdo_stmt.cpp
+++ b/source/pdo_sqlsrv/pdo_stmt.cpp
@@ -1311,7 +1311,7 @@ int pdo_sqlsrv_stmt_param_hook( _Inout_ pdo_stmt_t *stmt,
 
 
 // Returns a sqlsrv_phptype for a given SQL Server data type.
-sqlsrv_phptype pdo_sqlsrv_stmt::sql_type_to_php_type( _In_ SQLINTEGER sql_type, SQLUINTEGER size, bool prefer_string_over_stream )
+sqlsrv_phptype pdo_sqlsrv_stmt::sql_type_to_php_type( _In_ SQLINTEGER sql_type, _In_ SQLUINTEGER size, _In_ bool prefer_string_over_stream )
 {
     sqlsrv_phptype sqlsrv_phptype;
     int local_encoding = this->encoding();
diff --git a/source/pdo_sqlsrv/php_pdo_sqlsrv.h b/source/pdo_sqlsrv/php_pdo_sqlsrv.h
index e402c2ed..36b0eddf 100644
--- a/source/pdo_sqlsrv/php_pdo_sqlsrv.h
+++ b/source/pdo_sqlsrv/php_pdo_sqlsrv.h
@@ -264,7 +264,7 @@ struct pdo_sqlsrv_stmt : public sqlsrv_stmt {
 
     // driver specific conversion rules from a SQL Server/ODBC type to one of the SQLSRV_PHPTYPE_* constants
     // for PDO, everything is a string, so we return SQLSRV_PHPTYPE_STRING for all SQL types
-    virtual sqlsrv_phptype sql_type_to_php_type( _In_ SQLINTEGER sql_type, SQLUINTEGER size, bool prefer_string_to_stream );
+    virtual sqlsrv_phptype sql_type_to_php_type( _In_ SQLINTEGER sql_type, _In_ SQLUINTEGER size, _In_ bool prefer_string_to_stream );
 
     bool direct_query;                        // flag set if the query should be executed directly or prepared
     const char* direct_query_subst_string;    // if the query is direct, hold the substitution string if using named parameters
diff --git a/source/shared/core_conn.cpp b/source/shared/core_conn.cpp
index 04274576..4b488b16 100644
--- a/source/shared/core_conn.cpp
+++ b/source/shared/core_conn.cpp
@@ -527,7 +527,7 @@ void core_sqlsrv_get_client_info( _Inout_ sqlsrv_conn* conn, _Out_ zval *client_
 // Properly escaped means that any '}' should be escaped by a prior '}'.  It is assumed that 
 // the value will be surrounded by { and } by the caller after it has been validated
 
-bool core_is_conn_opt_value_escaped( _In_ const char* value, _Inout_ size_t value_len )
+bool core_is_conn_opt_value_escaped( _Inout_ const char* value, _Inout_ size_t value_len )
 {
     // if the value is already quoted, then only analyse the part inside the quotes and return it as 
     // unquoted since we quote it when adding it to the connection string.
diff --git a/source/shared/core_sqlsrv.h b/source/shared/core_sqlsrv.h
index 786465de..6f904f72 100644
--- a/source/shared/core_sqlsrv.h
+++ b/source/shared/core_sqlsrv.h
@@ -1199,7 +1199,7 @@ void core_sqlsrv_rollback( _Inout_ sqlsrv_conn* conn TSRMLS_DC );
 void core_sqlsrv_get_server_info( _Inout_ sqlsrv_conn* conn, _Out_ zval* server_info TSRMLS_DC );
 void core_sqlsrv_get_server_version( _Inout_ sqlsrv_conn* conn, _Inout_ zval *server_version TSRMLS_DC );
 void core_sqlsrv_get_client_info( _Inout_ sqlsrv_conn* conn, _Out_ zval *client_info TSRMLS_DC );
-bool core_is_conn_opt_value_escaped( _In_ const char* value, _Inout_ size_t value_len );
+bool core_is_conn_opt_value_escaped( _Inout_ const char* value, _Inout_ size_t value_len );
 size_t core_str_zval_is_true( _Inout_ zval* str_zval );
 bool core_is_authentication_option_valid( _In_z_ const char* value, _In_ size_t value_len );
 
@@ -1902,7 +1902,7 @@ namespace core {
         }
     }
 
-    inline void SQLDescribeCol( sqlsrv_stmt* stmt, SQLSMALLINT colno, _Out_writes_opt_(col_name_length) SQLCHAR* col_name, SQLSMALLINT col_name_length,
+    inline void SQLDescribeCol( _Inout_ sqlsrv_stmt* stmt, _In_ SQLSMALLINT colno, _Out_writes_opt_(col_name_length) SQLCHAR* col_name, _In_ SQLSMALLINT col_name_length,
                                 _Out_opt_ SQLSMALLINT* col_name_length_out, _Out_opt_ SQLSMALLINT* data_type, _Out_opt_ SQLULEN* col_size,
                                 _Out_opt_ SQLSMALLINT* decimal_digits, _Out_opt_ SQLSMALLINT* nullable TSRMLS_DC )
     {
diff --git a/source/sqlsrv/conn.cpp b/source/sqlsrv/conn.cpp
index 99d695c5..8da98f30 100644
--- a/source/sqlsrv/conn.cpp
+++ b/source/sqlsrv/conn.cpp
@@ -154,7 +154,7 @@ void validate_stmt_options( _Inout_ sqlsrv_context& ctx, _Inout_ zval* stmt_opti
 void add_conn_option_key( _Inout_ sqlsrv_context& ctx, _In_ zend_string* key, _In_ size_t key_len, 
                          _Inout_ HashTable* options_ht, _Inout_ zval* data TSRMLS_DC );
 void add_stmt_option_key( _Inout_ sqlsrv_context& ctx, _In_ zend_string* key, _In_ size_t key_len, _Inout_ HashTable* options_ht, _Inout_ zval* data TSRMLS_DC );
-int get_conn_option_key( _Inout_ sqlsrv_context& ctx, _In_ zend_string* key, _In_ size_t key_len, _In_ zval const* value_z TSRMLS_DC );   
+int get_conn_option_key( _Inout_ sqlsrv_context& ctx, _In_ zend_string* key, _In_ size_t key_len, _Inout_ zval const* value_z TSRMLS_DC );   
 int get_stmt_option_key( _In_ zend_string* key, _In_ size_t key_len TSRMLS_DC );
 
 }
@@ -1189,7 +1189,7 @@ void sqlsrv_conn_close_stmts( _Inout_ ss_sqlsrv_conn* conn TSRMLS_DC )
     conn->stmts = NULL;
 }
 
-int get_conn_option_key( _Inout_ sqlsrv_context& ctx, _In_ zend_string* key, _In_ size_t key_len, _In_ zval const* value_z TSRMLS_DC )    
+int get_conn_option_key( _Inout_ sqlsrv_context& ctx, _In_ zend_string* key, _In_ size_t key_len, _Inout_ zval const* value_z TSRMLS_DC )    
 {
     for( int i=0; SS_CONN_OPTS[ i ].conn_option_key != SQLSRV_CONN_OPTION_INVALID; ++i )
     {