diff --git a/makefile b/makefile
index 02be748..0c94d89 100644
--- a/makefile
+++ b/makefile
@@ -3,7 +3,7 @@
 YACC = src/grammar/$(GRAMMAR).y
 BUILDPATH = ./build
 LOCPATH = ./bin
-SRC = src/bot/handlers.c src/bot/context.c src/main.c src/grammar/types.h $(BUILDPATH)/$(GRAMMAR)/expenses.yy.c $(BUILDPATH)/$(GRAMMAR)/expenses.tab.c 
+SRC = src/grammar/types.c $(BUILDPATH)/$(GRAMMAR)/expenses.yy.c $(BUILDPATH)/$(GRAMMAR)/expenses.tab.c src/bot/handlers.c src/bot/context.c src/main.c
 INSTALLPATH = /usr/local
 CFLAGS = `pkg-config --cflags glib-2.0`
 LFLAGS =  -lstrophe `pkg-config --libs glib-2.0` 
diff --git a/src/bot/handlers.c b/src/bot/handlers.c
index 4ef20a6..47a2f22 100644
--- a/src/bot/handlers.c
+++ b/src/bot/handlers.c
@@ -60,7 +60,14 @@
 	intext = g_string_new(xmpp_stanza_get_text(xmpp_stanza_get_child_by_name(stanza, "body")));
 	
 	printf("Incoming message from %s: %s\n", xmpp_stanza_get_attribute(stanza, "from"), intext->str);
-	
+
+    /* parse with yyparse() */
+    if(grammar_parse_string(intext) == 0) {
+        printf("===== Parse OK!\n");
+    } else {
+        fprintf(stderr, "===== Parse error\n");
+    }
+
 	reply = xmpp_stanza_new(ctx);
 	xmpp_stanza_set_name(reply, "message");
 	xmpp_stanza_set_type(reply, xmpp_stanza_get_type(stanza)?xmpp_stanza_get_type(stanza):"chat");
@@ -80,7 +87,9 @@
 	
 	xmpp_send(conn, reply);
 	xmpp_stanza_release(reply);
-	free(replytext);
+	g_string_free(replytext, true);
+	g_string_free(intext, true);
+
 	return 1;
 }
 
diff --git a/src/bot/handlers.h b/src/bot/handlers.h
index 07a3618..8675f8a 100644
--- a/src/bot/handlers.h
+++ b/src/bot/handlers.h
@@ -7,6 +7,7 @@
 #include <string.h>
 #include <strophe.h>
 #include <glib.h>
+#include "../../build/expenses/expenses.tab.h"
 
 /* respond to version queries */
 int version_handler(xmpp_conn_t * const conn, xmpp_stanza_t * const stanza, void * const userdata);
diff --git a/src/grammar/expenses.l b/src/grammar/expenses.l
index c3aa604..ec4727c 100644
--- a/src/grammar/expenses.l
+++ b/src/grammar/expenses.l
@@ -1,10 +1,10 @@
 /* expenses.l: Expenses lexical analysis file
+ * TODO free memory allocated with g_string_new AFTER the parser is done (see grammar.y)
 */
 
 %{
 #include <stdio.h>
 #include <glib.h>
-#include "../../src/grammar/types.h"
 #include "expenses.tab.h"
 %}
                         
diff --git a/src/grammar/expenses.y b/src/grammar/expenses.y
index b1e0769..0cb32d3 100644
--- a/src/grammar/expenses.y
+++ b/src/grammar/expenses.y
@@ -15,10 +15,14 @@
 int yywrap()
 {
     return 1;
-} 
+}
 
 %}
 
+%code requires {
+#include "../../src/grammar/types.h"
+}
+
 %define parse.lac full
 %define parse.error verbose
 
@@ -48,7 +52,7 @@
 
 line:     '\n'
         | msg
-        | error { yyerrok; }
+        | error '\n' { yyerrok; }
 ;
 
 msg:      update value TOK_USER TOK_STR       { printf("update: %d %f %s %s\n", $1, $2, $3->str, $4->str); $$ = 0;}
diff --git a/src/grammar/types.c b/src/grammar/types.c
new file mode 100644
index 0000000..c4db6b3
--- /dev/null
+++ b/src/grammar/types.c
@@ -0,0 +1,11 @@
+/* function definition to parse a string instead of a file
+ */
+#include "types.h"
+
+int grammar_parse_string(const GString *buf) {
+    int res;
+    yy_scan_string(buf->str);
+    res = yyparse();
+    yylex_destroy();
+    return res;
+}
diff --git a/src/grammar/types.h b/src/grammar/types.h
index 716dd38..12d9e15 100644
--- a/src/grammar/types.h
+++ b/src/grammar/types.h
@@ -1,6 +1,8 @@
-/* additional types for expenses
+/* additional types for expenses grammar
  */
 #pragma once
+#include <stdio.h>
+#include <glib.h>
 
 typedef enum BotCommand {
     BOT_CMD_IN,
@@ -15,3 +17,11 @@
     BOT_TS_MONTHLY,
     BOT_TS_YEARLY
 } BotReportTimespan;
+
+int yylex();
+int yyparse();
+int yylex_destroy();
+typedef struct yy_buffer_state * YY_BUFFER_STATE;
+YY_BUFFER_STATE yy_scan_string(const char * str);
+
+int grammar_parse_string(const GString *buf);