diff --git a/src/expenses/grammar.y b/src/expenses/grammar.y
index 7784022..8cbb460 100644
--- a/src/expenses/grammar.y
+++ b/src/expenses/grammar.y
@@ -1,6 +1,7 @@
 %{
 #include <stdio.h>
 #include <glib.h>  /* For GString */
+#include <math.h>
 
 /* suppress warning about missing declarations */
 int yylex();
@@ -67,7 +68,7 @@
         | TOK_CMD_REMINDER TOK_INT
                 {
                     bot_set_last_command($1);
-                    bot_set_last_reminder($2);
+                    bot_set_last_reminder(abs($2));
                 }
         | TOK_CMD_DEL TOK_INT                 { printf("delete: %d\n", $2); $$ = 0; }
         | TOK_CMD_REPORT ts                   { printf("report: %d\n", $2); $$ = 0; }
diff --git a/src/expenses/task.c b/src/expenses/task.c
index dbcafbc..9f35cd3 100644
--- a/src/expenses/task.c
+++ b/src/expenses/task.c
@@ -38,7 +38,8 @@
         /* deep copy, but we don't care about from */
         reminder->minutes = g_tmp_lastReminder->minutes;
         reminder->from = g_string_new("");
-        /* free_bot_reminder(g_tmp_lastReminder); /\* can only be used once *\/ */
+        free_bot_reminder(g_tmp_lastReminder); /* can only be used once */
+        g_tmp_lastReminder = NULL;
     }
 
     return reminder;
@@ -50,6 +51,7 @@
     if(g_tmp_lastReminder) {
         fprintf(stderr, "WARNING: overwriting reminder. This should not happen.\n");
         free_bot_reminder(g_tmp_lastReminder); /* can only be used once */
+        g_tmp_lastReminder = NULL;
     }
     reminder = malloc(sizeof *reminder);
     reminder->minutes = minutes;
@@ -137,8 +139,13 @@
 void bot_cancel_task(const gchar * const user)
 {
     BotTask *task;
-    if ((task = g_hash_table_lookup(g_taskTable, user))) { /* value already present, stop reminder */
-        free_bot_task(task);
+    if(g_taskTable) {
+        if ((task = g_hash_table_lookup(g_taskTable, user))) { /* value already present, stop reminder */
+            free_bot_task(task);
+        }
+        if(g_tmp_lastReminder) {
+            free_bot_reminder(g_tmp_lastReminder);
+        }
+        g_hash_table_remove(g_taskTable, user);
     }
-    g_hash_table_remove(g_taskTable, user);
 }
diff --git a/src/expenses/types.c b/src/expenses/types.c
index 2fd7386..afce3c2 100644
--- a/src/expenses/types.c
+++ b/src/expenses/types.c
@@ -139,6 +139,8 @@
  BotReminder *reminder
 )
 {
-    g_string_free(reminder->from, true);
+    if(reminder->from) {
+        g_string_free(reminder->from, true);
+    }
     free(reminder);
 }