diff --git a/src/core/qgsexpressionlexer.ll b/src/core/qgsexpressionlexer.ll
index 6f971fd1d539..7abb33975986 100644
--- a/src/core/qgsexpressionlexer.ll
+++ b/src/core/qgsexpressionlexer.ll
@@ -132,45 +132,48 @@ string      "'"{str_char}*"'"
   \n        yylineno++;
 }
 
-"NOT"   { U_OP(uoNot); return NOT; }
-"AND"   { B_OP(boAnd); return AND; }
-"OR"    { B_OP(boOr);  return OR;  }
-
-"="     { B_OP(boEQ); return EQ; }
-"!="    { B_OP(boNE); return NE; }
-"<="    { B_OP(boLE); return LE; }
-">="    { B_OP(boGE); return GE; }
-"<>"    { B_OP(boNE); return NE; }
-"<"     { B_OP(boLT); return LT; }
-">"     { B_OP(boGT); return GT; }
-
-"~"     { B_OP(boRegexp); return REGEXP; }
-"LIKE"  { B_OP(boLike); return LIKE; }
-"ILIKE" { B_OP(boILike); return LIKE; }
-"IS"    { B_OP(boIs); return IS; }
-"||"    { B_OP(boConcat); return CONCAT; }
-
-"+"     { B_OP(boPlus); return PLUS; }
-"-"     { B_OP(boMinus); return MINUS; }
-"*"     { B_OP(boMul); return MUL; }
-"//"    { B_OP(boIntDiv); return INTDIV; }
-"/"     { B_OP(boDiv); return DIV; }
-"%"     { B_OP(boMod); return MOD; }
-"^"     { B_OP(boPow); return POW; }
-
-"IN"    {  return IN; }
-
-"NULL"	{ return NULLVALUE; }
-
-"CASE"  { return CASE; }
-"WHEN"  { return WHEN; }
-"THEN"  { return THEN; }
-"ELSE"  { return ELSE; }
-"END"   { return END;  }
-
-[()]    { return yytext[0]; }
-
-","     { return COMMA; }
+"NOT"               { U_OP(uoNot); return NOT; }
+"AND"               { B_OP(boAnd); return AND; }
+"OR"                { B_OP(boOr);  return OR;  }
+
+"="                 { B_OP(boEQ); return EQ; }
+"!="                { B_OP(boNE); return NE; }
+"<="                { B_OP(boLE); return LE; }
+">="                { B_OP(boGE); return GE; }
+"<>"                { B_OP(boNE); return NE; }
+"<"                 { B_OP(boLT); return LT; }
+">"                 { B_OP(boGT); return GT; }
+
+"~"                 { B_OP(boRegexp); return REGEXP; }
+"LIKE"              { B_OP(boLike); return LIKE; }
+"NOT"{white}"LIKE"  { B_OP(boNotLike); return LIKE; }
+"ILIKE"             { B_OP(boILike); return LIKE; }
+"NOT"{white}"ILIKE" { B_OP(boNotILike); return LIKE; }
+"IS"                { B_OP(boIs); return IS; }
+"IS"{white}"NOT"    { B_OP(boIsNot); return IS; }
+"||"                { B_OP(boConcat); return CONCAT; }
+
+"+"                 { B_OP(boPlus); return PLUS; }
+"-"                 { B_OP(boMinus); return MINUS; }
+"*"                 { B_OP(boMul); return MUL; }
+"//"                { B_OP(boIntDiv); return INTDIV; }
+"/"                 { B_OP(boDiv); return DIV; }
+"%"                 { B_OP(boMod); return MOD; }
+"^"                 { B_OP(boPow); return POW; }
+
+"IN"                { return IN; }
+
+"NULL"              { return NULLVALUE; }
+
+"CASE"              { return CASE; }
+"WHEN"              { return WHEN; }
+"THEN"              { return THEN; }
+"ELSE"              { return ELSE; }
+"END"               { return END;  }
+
+[()]                { return yytext[0]; }
+
+","                 { return COMMA; }
 
 {num_float}  { yylval->numberFloat = cLocale.toDouble( QString::fromAscii(yytext) ); return NUMBER_FLOAT; }
 {num_int}  {
diff --git a/src/core/qgsexpressionparser.yy b/src/core/qgsexpressionparser.yy
index 13351cd8ba2e..0135bf7df82c 100644
--- a/src/core/qgsexpressionparser.yy
+++ b/src/core/qgsexpressionparser.yy
@@ -168,9 +168,7 @@ expression:
     | expression GT expression        { $$ = BINOP($2, $1, $3); }
     | expression REGEXP expression    { $$ = BINOP($2, $1, $3); }
     | expression LIKE expression      { $$ = BINOP($2, $1, $3); }
-    | expression NOT LIKE expression  { $$ = BINOP($3==QgsExpression::boLike ? QgsExpression::boNotLike : QgsExpression::boNotILike, $1, $4); }
     | expression IS expression        { $$ = BINOP($2, $1, $3); }
-    | expression IS NOT expression    { $$ = BINOP(QgsExpression::boIsNot, $1, $4); }
     | expression PLUS expression      { $$ = BINOP($2, $1, $3); }
     | expression MINUS expression     { $$ = BINOP($2, $1, $3); }
     | expression MUL expression       { $$ = BINOP($2, $1, $3); }
@@ -181,7 +179,6 @@ expression:
     | expression CONCAT expression    { $$ = BINOP($2, $1, $3); }
     | NOT expression                  { $$ = new QgsExpression::NodeUnaryOperator($1, $2); }
     | '(' expression ')'              { $$ = $2; }
-
     | FUNCTION '(' exp_list ')'
         {
           int fnIndex = QgsExpression::functionIndex(*$1);