diff --git a/pql/ast.go b/pql/ast.go
index 13a989b03..9555f9d90 100644
--- a/pql/ast.go
+++ b/pql/ast.go
@@ -161,19 +161,7 @@ func (c *Call) String() string {
 		if i > 0 {
 			buf.WriteString(", ")
 		}
-
-		switch v := c.Args[key].(type) {
-		case string:
-			fmt.Fprintf(&buf, "%v=%q", key, v)
-		case []interface{}:
-			fmt.Fprintf(&buf, "%v=%s", key, joinInterfaceSlice(v))
-		case []uint64:
-			fmt.Fprintf(&buf, "%v=%s", key, joinUint64Slice(v))
-		case time.Time:
-			fmt.Fprintf(&buf, "%v=\"%s\"", key, v.Format(TimeFormat))
-		default:
-			fmt.Fprintf(&buf, "%v=%v", key, v)
-		}
+		fmt.Fprintf(&buf, "%v=%s", key, FormatValue(c.Args[key]))
 	}
 
 	// Write closing.
@@ -210,6 +198,35 @@ func (c *Call) IsInverse(rowLabel, columnLabel string) bool {
 	return false
 }
 
+// Condition represents an operation & value.
+// When used in an argument map it represents a binary expression.
+type Condition struct {
+	Op    Token
+	Value interface{}
+}
+
+// String returns the string representation of the condition.
+func (cond *Condition) String() string {
+	return fmt.Sprintf("%s %s", cond.Op.String(), FormatValue(cond.Value))
+}
+
+func FormatValue(v interface{}) string {
+	switch v := v.(type) {
+	case string:
+		return fmt.Sprintf("%q", v)
+	case []interface{}:
+		return fmt.Sprintf("%s", joinInterfaceSlice(v))
+	case []uint64:
+		return fmt.Sprintf("%s", joinUint64Slice(v))
+	case time.Time:
+		return fmt.Sprintf("\"%s\"", v.Format(TimeFormat))
+	case *Condition:
+		return v.String()
+	default:
+		return fmt.Sprintf("%v", v)
+	}
+}
+
 // CopyArgs returns a copy of m.
 func CopyArgs(m map[string]interface{}) map[string]interface{} {
 	other := make(map[string]interface{}, len(m))
diff --git a/pql/parser.go b/pql/parser.go
index 048f6a664..f0d5feeae 100644
--- a/pql/parser.go
+++ b/pql/parser.go
@@ -161,9 +161,14 @@ func (p *Parser) parseArgs() (map[string]interface{}, error) {
 		}
 		key := lit
 
-		// Expect '=' next.
-		if tok, pos, lit := p.scanIgnoreWhitespace(); tok != EQ {
-			return nil, parseErrorf(pos, "expected equals sign, found %q", lit)
+		// Expect '=' or a comparison next.
+		var op Token
+		switch tok, pos, lit := p.scanIgnoreWhitespace(); tok {
+		case ASSIGN:
+		case EQ, LT, LTE, GT, GTE:
+			op = tok
+		default:
+			return nil, parseErrorf(pos, "expected equals sign or comparison operator, found %q", lit)
 		}
 
 		// Parse value.
@@ -209,6 +214,11 @@ func (p *Parser) parseArgs() (map[string]interface{}, error) {
 			return nil, parseErrorf(pos, "argument key already used: %s", key)
 		}
 
+		// If op is specified then create a condition.
+		if op != 0 {
+			value = &Condition{Op: op, Value: value}
+		}
+
 		// Add key/value pair to arguments.
 		args[key] = value
 
diff --git a/pql/parser_test.go b/pql/parser_test.go
index 8cb8a2858..736a9c7f8 100644
--- a/pql/parser_test.go
+++ b/pql/parser_test.go
@@ -169,4 +169,24 @@ func TestParser_Parse(t *testing.T) {
 			t.Fatalf("unexpected call: %#v", q.Calls[0])
 		}
 	})
+
+	// Parse with condition arguments.
+	t.Run("WithCondition", func(t *testing.T) {
+		q, err := pql.ParseString(`MyCall(key=foo, x == 12.25, y >= 100)`)
+		if err != nil {
+			t.Fatal(err)
+		} else if !reflect.DeepEqual(q.Calls[0],
+			&pql.Call{
+				Name: "MyCall",
+				Args: map[string]interface{}{
+					"key": "foo",
+					"x":   &pql.Condition{Op: pql.EQ, Value: 12.25},
+					"y":   &pql.Condition{Op: pql.GTE, Value: int64(100)},
+				},
+			},
+		) {
+			t.Fatalf("unexpected call: %#v", q.Calls[0])
+		}
+	})
+
 }
diff --git a/pql/scanner.go b/pql/scanner.go
index a559d8ccb..38fd7d6fc 100644
--- a/pql/scanner.go
+++ b/pql/scanner.go
@@ -59,26 +59,38 @@ func (s *Scanner) Scan() (tok Token, pos Pos, lit string) {
 	// Otherwise parse individual characters.
 	switch ch {
 	case eof:
-		tok = EOF
-		return
+		return EOF, pos, ""
 	case '=':
-		tok = EQ
+		if next := s.read(); next == '=' {
+			return EQ, pos, "=="
+		}
+		s.unread()
+		return ASSIGN, pos, string(ch)
+	case '<':
+		if next := s.read(); next == '=' {
+			return LTE, pos, "<="
+		}
+		s.unread()
+		return LT, pos, string(ch)
+	case '>':
+		if next := s.read(); next == '=' {
+			return GTE, pos, ">="
+		}
+		s.unread()
+		return GT, pos, string(ch)
 	case ',':
-		tok = COMMA
+		return COMMA, pos, string(ch)
 	case '(':
-		tok = LPAREN
+		return LPAREN, pos, string(ch)
 	case ')':
-		tok = RPAREN
+		return RPAREN, pos, string(ch)
 	case '[':
-		tok = LBRACK
+		return LBRACK, pos, string(ch)
 	case ']':
-		tok = RBRACK
+		return RBRACK, pos, string(ch)
 	default:
-		tok = ILLEGAL
+		return ILLEGAL, pos, string(ch)
 	}
-
-	lit = string(ch)
-	return
 }
 
 // read returns the next code point from the underlying reader and updates the pos.
diff --git a/pql/scanner_test.go b/pql/scanner_test.go
index 5b7a06b2f..49d272ce5 100644
--- a/pql/scanner_test.go
+++ b/pql/scanner_test.go
@@ -23,42 +23,50 @@ import (
 
 func TestScanner_Scan(t *testing.T) {
 	var tests = []struct {
-		s   string
-		tok pql.Token
-		lit string
-		pos pql.Pos
+		name string
+		s    string
+		tok  pql.Token
+		lit  string
+		pos  pql.Pos
 	}{
 		// Special tokens (EOF, ILLEGAL, WS)
-		{s: ``, tok: pql.EOF},
-		{s: `#`, tok: pql.ILLEGAL, lit: `#`},
-		{s: ` `, tok: pql.WS, lit: " "},
-		{s: "\t", tok: pql.WS, lit: "\t"},
-		{s: "\n", tok: pql.WS, lit: "\n"},
+		{name: "EOF", s: ``, tok: pql.EOF},
+		{name: "ILLEGAL", s: `#`, tok: pql.ILLEGAL, lit: `#`},
+		{name: "WS/SPACE", s: ` `, tok: pql.WS, lit: " "},
+		{name: "WS/TAB", s: "\t", tok: pql.WS, lit: "\t"},
+		{name: "WS/NEWLINE", s: "\n", tok: pql.WS, lit: "\n"},
 
-		{s: `=`, tok: pql.EQ, lit: `=`},
-		{s: `,`, tok: pql.COMMA, lit: `,`},
-		{s: `(`, tok: pql.LPAREN, lit: `(`},
-		{s: `)`, tok: pql.RPAREN, lit: `)`},
-		{s: `[`, tok: pql.LBRACK, lit: `[`},
-		{s: `]`, tok: pql.RBRACK, lit: `]`},
+		{name: "ASSIGN", s: `=`, tok: pql.ASSIGN, lit: `=`},
+		{name: "EQ", s: `==`, tok: pql.EQ, lit: `==`},
+		{name: "LT", s: `<`, tok: pql.LT, lit: `<`},
+		{name: "LTE", s: `<=`, tok: pql.LTE, lit: `<=`},
+		{name: "GT", s: `>`, tok: pql.GT, lit: `>`},
+		{name: "GTE", s: `>=`, tok: pql.GTE, lit: `>=`},
+		{name: "COMMA", s: `,`, tok: pql.COMMA, lit: `,`},
+		{name: "LPAREN", s: `(`, tok: pql.LPAREN, lit: `(`},
+		{name: "RPAREN", s: `)`, tok: pql.RPAREN, lit: `)`},
+		{name: "LBRACK", s: `[`, tok: pql.LBRACK, lit: `[`},
+		{name: "RBRACK", s: `]`, tok: pql.RBRACK, lit: `]`},
 
-		{s: `foo`, tok: pql.IDENT, lit: `foo`},
-		{s: `100`, tok: pql.INTEGER, lit: `100`},
-		{s: `100.3`, tok: pql.FLOAT, lit: `100.3`},
+		{name: "IDENT", s: `foo`, tok: pql.IDENT, lit: `foo`},
+		{name: "INTEGER", s: `100`, tok: pql.INTEGER, lit: `100`},
+		{name: "FLOAT", s: `100.3`, tok: pql.FLOAT, lit: `100.3`},
 
-		{s: `all`, tok: pql.ALL, lit: `all`},
-		{s: `ALL`, tok: pql.ALL, lit: `ALL`}, // case insensitive
+		{name: "ALL", s: `all`, tok: pql.ALL, lit: `all`},
+		{name: "ALL/CASE", s: `ALL`, tok: pql.ALL, lit: `ALL`}, // case insensitive
 	}
 
 	for i, tt := range tests {
-		s := pql.NewScanner(strings.NewReader(tt.s))
-		tok, pos, lit := s.Scan()
-		if tt.tok != tok {
-			t.Errorf("%d. %q token mismatch: exp=%q got=%q <%q>", i, tt.s, tt.tok, tok, lit)
-		} else if tt.pos.Line != pos.Line || tt.pos.Char != pos.Char {
-			t.Errorf("%d. %q pos mismatch: exp=%#v got=%#v", i, tt.s, tt.pos, pos)
-		} else if tt.lit != lit {
-			t.Errorf("%d. %q literal mismatch: exp=%q got=%q", i, tt.s, tt.lit, lit)
-		}
+		t.Run(tt.name, func(t *testing.T) {
+			s := pql.NewScanner(strings.NewReader(tt.s))
+			tok, pos, lit := s.Scan()
+			if tt.tok != tok {
+				t.Errorf("%d. %q token mismatch: exp=%q got=%q <%q>", i, tt.s, tt.tok, tok, lit)
+			} else if tt.pos.Line != pos.Line || tt.pos.Char != pos.Char {
+				t.Errorf("%d. %q pos mismatch: exp=%#v got=%#v", i, tt.s, tt.pos, pos)
+			} else if tt.lit != lit {
+				t.Errorf("%d. %q literal mismatch: exp=%q got=%q", i, tt.s, tt.lit, lit)
+			}
+		})
 	}
 }
diff --git a/pql/token.go b/pql/token.go
index 4d71117af..1327df9ce 100644
--- a/pql/token.go
+++ b/pql/token.go
@@ -37,7 +37,12 @@ const (
 	ALL
 	keyword_end
 
-	EQ     // =
+	ASSIGN // =
+	EQ     // ==
+	LT     // <
+	LTE    // <=
+	GT     // >
+	GTE    // >=
 	COMMA  // ,
 	LPAREN // (
 	RPAREN // )
@@ -56,7 +61,12 @@ var tokens = [...]string{
 
 	ALL: "ALL",
 
-	EQ:     "=",
+	ASSIGN: "=",
+	EQ:     "==",
+	LT:     "<",
+	LTE:    "<=",
+	GT:     ">",
+	GTE:    ">=",
 	COMMA:  ",",
 	LPAREN: "(",
 	RPAREN: ")",