diff --git a/filter-parser/src/condition.rs b/filter-parser/src/condition.rs
index c63f1d926..cbf73b96a 100644
--- a/filter-parser/src/condition.rs
+++ b/filter-parser/src/condition.rs
@@ -44,8 +44,7 @@ impl<'a> Condition<'a> {
         }
     }
 }
-
-/// condition      = value ("==" | ">" ...) value
+/// condition      = value ("=" | "!=" | ">" | ">=" | "<" | "<=") value
 pub fn parse_condition(input: Span) -> IResult<FilterCondition> {
     let operator = alt((tag("<="), tag(">="), tag("!="), tag("<"), tag(">"), tag("=")));
     let (input, (fid, op, value)) = tuple((parse_value, operator, cut(parse_value)))(input)?;
@@ -69,7 +68,7 @@ pub fn parse_exists(input: Span) -> IResult<FilterCondition> {
 
     Ok((input, FilterCondition::Condition { fid: key.into(), op: Exists }))
 }
-/// exist          = value "NOT" WS* "EXISTS"
+/// exist          = value "NOT" WS+ "EXISTS"
 pub fn parse_not_exists(input: Span) -> IResult<FilterCondition> {
     let (input, key) = parse_value(input)?;
 
@@ -77,10 +76,10 @@ pub fn parse_not_exists(input: Span) -> IResult<FilterCondition> {
     Ok((input, FilterCondition::Condition { fid: key.into(), op: NotExists }))
 }
 
-/// to             = value value TO value
+/// to             = value value "TO" WS+ value
 pub fn parse_to(input: Span) -> IResult<FilterCondition> {
-    let (input, (key, from, _, to)) =
-        tuple((parse_value, parse_value, tag("TO"), cut(parse_value)))(input)?;
+    let (input, (key, from, _, _, to)) =
+        tuple((parse_value, parse_value, tag("TO"), multispace1, cut(parse_value)))(input)?;
 
     Ok((input, FilterCondition::Condition { fid: key, op: Between { from, to } }))
 }
diff --git a/filter-parser/src/lib.rs b/filter-parser/src/lib.rs
index 5cce5f4c3..01be432d7 100644
--- a/filter-parser/src/lib.rs
+++ b/filter-parser/src/lib.rs
@@ -3,19 +3,19 @@
 //! ```text
 //! filter         = expression EOF
 //! expression     = or
-//! or             = and ("OR" and)
-//! and            = not ("AND" not)*
-//! not            = ("NOT" not) | primary
-//! primary        = (WS* "("  expression ")" WS*) | geoRadius | condition | exists | not_exists | to
-//! condition      = value ("==" | ">" ...) value
+//! or             = and ("OR" WS+ and)*
+//! and            = not ("AND" WS+ not)*
+//! not            = ("NOT" WS+ not) | primary
+//! primary        = (WS* "(" WS* expression WS* ")" WS*) | geoRadius | condition | exists | not_exists | to
+//! condition      = value ("=" | "!=" | ">" | ">=" | "<" | "<=") value
 //! exists         = value "EXISTS"
-//! not_exists     = value "NOT" WS* "EXISTS"
-//! to             = value value "TO" value
-//! value          = WS* ( word | singleQuoted | doubleQuoted) WS*
+//! not_exists     = value "NOT" WS+ "EXISTS"
+//! to             = value value "TO" WS+ value
+//! value          = WS* ( word | singleQuoted | doubleQuoted) WS+
 //! singleQuoted   = "'" .* all but quotes "'"
 //! doubleQuoted   = "\"" .* all but double quotes "\""
 //! word           = (alphanumeric | _ | - | .)+
-//! geoRadius      = WS* "_geoRadius(" WS* float WS* "," WS* float WS* "," float WS* ")"
+//! geoRadius      = "_geoRadius(" WS* float WS* "," WS* float WS* "," float WS* ")"
 //! ```
 //!
 //! Other BNF grammar used to handle some specific errors:
@@ -50,7 +50,7 @@ use error::{cut_with_err, NomErrorExt};
 pub use error::{Error, ErrorKind};
 use nom::branch::alt;
 use nom::bytes::complete::tag;
-use nom::character::complete::{char, multispace0};
+use nom::character::complete::{char, multispace0, multispace1};
 use nom::combinator::{cut, eof, map};
 use nom::multi::{many0, separated_list1};
 use nom::number::complete::recognize_float;
@@ -170,11 +170,11 @@ fn ws<'a, O>(inner: impl FnMut(Span<'a>) -> IResult<O>) -> impl FnMut(Span<'a>)
     delimited(multispace0, inner, multispace0)
 }
 
-/// or             = and ("OR" and)*
+/// or             = and ("OR" WS+ and)*
 fn parse_or(input: Span) -> IResult<FilterCondition> {
     let (input, lhs) = parse_and(input)?;
     // if we found a `OR` then we MUST find something next
-    let (input, ors) = many0(preceded(ws(tag("OR")), cut(parse_and)))(input)?;
+    let (input, ors) = many0(preceded(ws(tuple((tag("OR"), multispace1))), cut(parse_and)))(input)?;
 
     let expr = ors
         .into_iter()
@@ -186,24 +186,28 @@ fn parse_or(input: Span) -> IResult<FilterCondition> {
 fn parse_and(input: Span) -> IResult<FilterCondition> {
     let (input, lhs) = parse_not(input)?;
     // if we found a `AND` then we MUST find something next
-    let (input, ors) = many0(preceded(ws(tag("AND")), cut(parse_not)))(input)?;
+    let (input, ors) =
+        many0(preceded(ws(tuple((tag("AND"), multispace1))), cut(parse_not)))(input)?;
     let expr = ors
         .into_iter()
         .fold(lhs, |acc, branch| FilterCondition::And(Box::new(acc), Box::new(branch)));
     Ok((input, expr))
 }
 
-/// not            = ("NOT" not) | primary
-/// We can have multiple consecutive not, eg: `NOT NOT channel = mv`.
+/// not            = ("NOT" WS+ not) | primary
+/// We can have multiple consecutive not, eg: `NOT NOT channel = mv`.
 /// If we parse a `NOT` we MUST parse something behind.
 fn parse_not(input: Span) -> IResult<FilterCondition> {
-    alt((map(preceded(tag("NOT"), cut(parse_not)), |e| e.negate()), parse_primary))(input)
+    alt((
+        map(preceded(ws(tuple((tag("NOT"), multispace1))), cut(parse_not)), |e| e.negate()),
+        parse_primary,
+    ))(input)
 }
 
 /// geoRadius      = WS* "_geoRadius(float WS* "," WS* float WS* "," WS* float)
 /// If we parse `_geoRadius` we MUST parse the rest of the expression.
 fn parse_geo_radius(input: Span) -> IResult<FilterCondition> {
-    // we want to forbid space BEFORE the _geoRadius but not after
+    // we want to allow space BEFORE the _geoRadius but not after
     let parsed = preceded(
         tuple((multispace0, tag("_geoRadius"))),
         // if we were able to parse `_geoRadius` and can't parse the rest of the input we return a failure
@@ -238,7 +242,7 @@ fn parse_geo_point(input: Span) -> IResult<FilterCondition> {
     Err(nom::Err::Failure(Error::new_from_kind(input, ErrorKind::ReservedGeo("_geoPoint"))))
 }
 
-/// primary        = (WS* "("  expression ")" WS*) | geoRadius | condition | to
+/// primary        = (WS* "(" WS* expression WS* ")" WS*) | geoRadius | condition | exists | not_exists | to
 fn parse_primary(input: Span) -> IResult<FilterCondition> {
     alt((
         // if we find a first parenthesis, then we must parse an expression and find the closing parenthesis
@@ -620,7 +624,7 @@ pub mod tests {
             ("OR", "Was expecting an operation `=`, `!=`, `>=`, `>`, `<=`, `<`, `TO`, `EXISTS`, `NOT EXISTS`, or `_geoRadius` at `OR`."),
             ("AND", "Was expecting an operation `=`, `!=`, `>=`, `>`, `<=`, `<`, `TO`, `EXISTS`, `NOT EXISTS`, or `_geoRadius` at `AND`."),
             ("channel Ponce", "Was expecting an operation `=`, `!=`, `>=`, `>`, `<=`, `<`, `TO`, `EXISTS`, `NOT EXISTS`, or `_geoRadius` at `channel Ponce`."),
-            ("channel = Ponce OR", "Was expecting an operation `=`, `!=`, `>=`, `>`, `<=`, `<`, `TO`, `EXISTS`, `NOT EXISTS`, or `_geoRadius` but instead got nothing."),
+            ("channel = Ponce OR", "Found unexpected characters at the end of the filter: `OR`. You probably forgot an `OR` or an `AND` rule."),
             ("_geoRadius", "The `_geoRadius` filter expects three arguments: `_geoRadius(latitude, longitude, radius)`."),
             ("_geoRadius = 12", "The `_geoRadius` filter expects three arguments: `_geoRadius(latitude, longitude, radius)`."),
             ("_geoPoint(12, 13, 14)", "`_geoPoint` is a reserved keyword and thus can't be used as a filter expression. Use the `_geoRadius(latitude, longitude, distance) built-in rule to filter on `_geo` coordinates."),
@@ -631,6 +635,9 @@ pub mod tests {
             ("channel = mv OR (followers >= 1000", "Expression `(followers >= 1000` is missing the following closing delimiter: `)`."),
             ("channel = mv OR followers >= 1000)", "Found unexpected characters at the end of the filter: `)`. You probably forgot an `OR` or an `AND` rule."),
             ("colour NOT EXIST", "Was expecting an operation `=`, `!=`, `>=`, `>`, `<=`, `<`, `TO`, `EXISTS`, `NOT EXISTS`, or `_geoRadius` at `colour NOT EXIST`."),
+            ("subscribers 100 TO1000", "Was expecting an operation `=`, `!=`, `>=`, `>`, `<=`, `<`, `TO`, `EXISTS`, `NOT EXISTS`, or `_geoRadius` at `subscribers 100 TO1000`."),
+            ("channel = ponce ORdog != 'bernese mountain'", "Found unexpected characters at the end of the filter: `ORdog != \\'bernese mountain\\'`. You probably forgot an `OR` or an `AND` rule."),
+            ("channel = ponce AND'dog' != 'bernese mountain'", "Found unexpected characters at the end of the filter: `AND\\'dog\\' != \\'bernese mountain\\'`. You probably forgot an `OR` or an `AND` rule."),
         ];
 
         for (input, expected) in test_case {
diff --git a/filter-parser/src/value.rs b/filter-parser/src/value.rs
index 18ae58ae5..22da6a0df 100644
--- a/filter-parser/src/value.rs
+++ b/filter-parser/src/value.rs
@@ -48,7 +48,7 @@ fn quoted_by(quote: char, input: Span) -> IResult<Token> {
     ))
 }
 
-/// value          = WS* ( word | singleQuoted | doubleQuoted) WS*
+/// value          = WS* ( word | singleQuoted | doubleQuoted) WS+
 pub fn parse_value<'a>(input: Span<'a>) -> IResult<Token<'a>> {
     // to get better diagnostic message we are going to strip the left whitespaces from the input right now
     let (input, _) = take_while(char::is_whitespace)(input)?;