diff --git a/client/mysqltest.cc b/client/mysqltest.cc
index c945f20a240..d1b26363d4d 100644
--- a/client/mysqltest.cc
+++ b/client/mysqltest.cc
@@ -227,8 +227,9 @@ typedef struct
   int str_val_len;
   int int_val;
   int alloced_len;
-  int int_dirty; /* do not update string if int is updated until first read */
-  int alloced;
+  bool int_dirty; /* do not update string if int is updated until first read */
+  bool is_int;
+  bool alloced;
 } VAR;
 
 /*Perl/shell-like variable registers */
@@ -1954,6 +1955,21 @@ static void var_free(void *v)
 
 C_MODE_END
 
+void var_set_int(VAR *v, const char *str)
+{
+  char *endptr;
+  /* Initially assume not a number */
+  v->int_val= 0;
+  v->is_int= false;
+  v->int_dirty= false;
+  if (!str) return;
+  
+  v->int_val = (int) strtol(str, &endptr, 10);
+  /* It is an int if strtol consumed something up to end/space/tab */
+  if (endptr > str && (!*endptr || *endptr == ' ' || *endptr == '\t'))
+    v->is_int= true;
+}
+
 
 VAR *var_init(VAR *v, const char *name, int name_len, const char *val,
               int val_len)
@@ -1988,11 +2004,10 @@ VAR *var_init(VAR *v, const char *name, int name_len, const char *val,
     memcpy(tmp_var->str_val, val, val_len);
     tmp_var->str_val[val_len]= 0;
   }
+  var_set_int(tmp_var, val);
   tmp_var->name_len = name_len;
   tmp_var->str_val_len = val_len;
   tmp_var->alloced_len = val_alloc_len;
-  tmp_var->int_val = (val) ? atoi(val) : 0;
-  tmp_var->int_dirty = 0;
   return tmp_var;
 }
 
@@ -2053,7 +2068,7 @@ VAR* var_get(const char *var_name, const char **var_name_end, my_bool raw,
   if (!raw && v->int_dirty)
   {
     sprintf(v->str_val, "%d", v->int_val);
-    v->int_dirty = 0;
+    v->int_dirty= false;
     v->str_val_len = strlen(v->str_val);
   }
   if (var_name_end)
@@ -2115,7 +2130,7 @@ void var_set(const char *var_name, const char *var_name_end,
     if (v->int_dirty)
     {
       sprintf(v->str_val, "%d", v->int_val);
-      v->int_dirty= 0;
+      v->int_dirty=false;
       v->str_val_len= strlen(v->str_val);
     }
     /* setenv() expects \0-terminated strings */
@@ -2421,6 +2436,7 @@ void var_set_query_get_value(struct st_command *command, VAR *var)
 void var_copy(VAR *dest, VAR *src)
 {
   dest->int_val= src->int_val;
+  dest->is_int= src->is_int;
   dest->int_dirty= src->int_dirty;
 
   /* Alloc/realloc data for str_val in dest */
@@ -2504,9 +2520,7 @@ void eval_expr(VAR *v, const char *p, const char **p_end)
     v->str_val_len = new_val_len;
     memcpy(v->str_val, p, new_val_len);
     v->str_val[new_val_len] = 0;
-    v->int_val=atoi(p);
-    DBUG_PRINT("info", ("atoi on '%s', returns: %d", p, v->int_val));
-    v->int_dirty=0;
+    var_set_int(v, p);
   }
   DBUG_VOID_RETURN;
 }
@@ -2853,6 +2867,8 @@ int do_modify_var(struct st_command *command,
     die("The argument to %.*s must be a variable (start with $)",
         command->first_word_len, command->query);
   v= var_get(p, &p, 1, 0);
+  if (! v->is_int)
+    die("Cannot perform inc/dec on a non-numeric value");
   switch (op) {
   case DO_DEC:
     v->int_val--;
@@ -2864,7 +2880,7 @@ int do_modify_var(struct st_command *command,
     die("Invalid operator to do_modify_var");
     break;
   }
-  v->int_dirty= 1;
+  v->int_dirty= true;
   command->last_argument= (char*)++p;
   return 0;
 }
diff --git a/mysql-test/r/mysqltest.result b/mysql-test/r/mysqltest.result
index 650cc069b7f..d7597599f02 100644
--- a/mysql-test/r/mysqltest.result
+++ b/mysql-test/r/mysqltest.result
@@ -369,23 +369,24 @@ mysqltest: At line 1: Missing required argument 'sleep_delay' to command 'real_s
 mysqltest: At line 1: Invalid argument to sleep "abc"
 mysqltest: At line 1: Invalid argument to real_sleep "abc"
 1
-2
 101
-hej
-1
+-99
 mysqltest: At line 1: Missing argument to inc
 mysqltest: At line 1: The argument to inc must be a variable (start with $)
+mysqltest: At line 1: Cannot perform inc/dec on a non-numeric value
 mysqltest: At line 1: End of line junk detected: "1000"
-4
-4
+mysqltest: At line 1: Cannot perform inc/dec on a non-numeric value
+mysqltest: At line 1: Cannot perform inc/dec on a non-numeric value
+-96
+-96
 -1
--2
 99
-hej
--1
 mysqltest: At line 1: Missing argument to dec
 mysqltest: At line 1: The argument to dec must be a variable (start with $)
+mysqltest: At line 1: Cannot perform inc/dec on a non-numeric value
 mysqltest: At line 1: End of line junk detected: "1000"
+mysqltest: At line 1: Cannot perform inc/dec on a non-numeric value
+mysqltest: At line 1: Cannot perform inc/dec on a non-numeric value
 mysqltest: At line 1: Missing arguments to system, nothing to do!
 mysqltest: At line 1: Missing arguments to system, nothing to do!
 system command 'NonExistsinfComamdn 2> /dev/null' failed
diff --git a/mysql-test/t/mysqltest.test b/mysql-test/t/mysqltest.test
index c054b163c0c..45dbb4a5c8d 100644
--- a/mysql-test/t/mysqltest.test
+++ b/mysql-test/t/mysqltest.test
@@ -1006,16 +1006,13 @@ EOF
 # ----------------------------------------------------------------------------
 # Test inc
 # ----------------------------------------------------------------------------
-inc $i;
-echo $i;
+let $i= 0;
 inc $i;
 echo $i;
 let $i=100;
 inc $i;
 echo $i;
-
-let $i=hej;
-echo $i;
+let $i= -100;
 inc $i;
 echo $i;
 
@@ -1024,7 +1021,13 @@ echo $i;
 --error 1
 --exec echo "inc i;" | $MYSQL_TEST 2>&1
 --error 1
+--exec echo "inc \$i;" | $MYSQL_TEST 2>&1
+--error 1
 --exec echo "let \$i=100; inc \$i 1000; echo \$i;" | $MYSQL_TEST 2>&1
+--error 1
+--exec echo "let \$i=text; inc \$i; echo \$i;" | $MYSQL_TEST 2>&1
+--error 1
+--exec echo "let \$i=10cc; inc \$i; echo \$i;" | $MYSQL_TEST 2>&1
 
 inc $i; inc $i; inc $i; --echo $i
 echo $i;
@@ -1034,25 +1037,25 @@ echo $i;
 # Test dec
 # ----------------------------------------------------------------------------
 
-dec $d;
-echo $d;
+let $d= 0;
 dec $d;
 echo $d;
 let $d=100;
 dec $d;
 echo $d;
 
-let $d=hej;
-echo $d;
-dec $d;
-echo $d;
-
 --error 1
 --exec echo "dec;" | $MYSQL_TEST 2>&1
 --error 1
 --exec echo "dec i;" | $MYSQL_TEST 2>&1
 --error 1
+--exec echo "dec \$i;" | $MYSQL_TEST 2>&1
+--error 1
 --exec echo "let \$i=100; dec \$i 1000; echo \$i;" | $MYSQL_TEST 2>&1
+--error 1
+--exec echo "let \$i=text; dec \$i; echo \$i;" | $MYSQL_TEST 2>&1
+--error 1
+--exec echo "let \$i=10cc; dec \$i; echo \$i;" | $MYSQL_TEST 2>&1
 
 
 # ----------------------------------------------------------------------------