diff --git a/parser.go b/parser.go
index f98303e..8c5d0dc 100644
--- a/parser.go
+++ b/parser.go
@@ -11,7 +11,7 @@ type parser struct {
 
 	cfg *ParserConfig
 
-	errors ScannerErrorList
+	errors ParserErrorList
 
 	tok Token
 	lit string
@@ -36,8 +36,12 @@ func ParseArgs(args []string, pCfg *ParserConfig) (*ParseTree, error) {
 	return p.parseArgs()
 }
 
+func (p *parser) addError(msg string) {
+	p.errors.Add(Position{Column: int(p.pos)}, msg)
+}
+
 func (p *parser) init(r io.Reader, pCfg *ParserConfig) {
-	p.errors = ScannerErrorList{}
+	p.errors = ParserErrorList{}
 
 	if pCfg == nil {
 		pCfg = POSIXyParserConfig
@@ -156,7 +160,7 @@ func (p *parser) parseCommand(cCfg *CommandConfig) Node {
 		case ASSIGN:
 			tracef("parseCommand(...) error on bare %s", p.tok)
 
-			p.errors.Add(Position{Column: int(p.pos)}, "invalid bare assignment")
+			p.addError("invalid bare assignment")
 
 			break
 		default:
@@ -203,6 +207,8 @@ func (p *parser) parseShortFlag(flCfgMap map[string]FlagConfig) Node {
 
 	flCfg, ok := flCfgMap[node.Name]
 	if !ok {
+		p.addError(fmt.Sprintf("unknown flag %q", node.Name))
+
 		return node
 	}
 
@@ -214,6 +220,8 @@ func (p *parser) parseLongFlag(flCfgMap map[string]FlagConfig) Node {
 
 	flCfg, ok := flCfgMap[node.Name]
 	if !ok {
+		p.addError(fmt.Sprintf("unknown flag %q", node.Name))
+
 		return node
 	}
 
@@ -230,11 +238,15 @@ func (p *parser) parseCompoundShortFlag(flCfgMap map[string]FlagConfig) Node {
 
 		if i == len(withoutFlagPrefix)-1 {
 			flCfg, ok := flCfgMap[node.Name]
-			if ok {
-				flagNodes = append(flagNodes, p.parseConfiguredFlag(node, flCfg))
+			if !ok {
+				p.addError(fmt.Sprintf("unknown flag %q", node.Name))
 
 				continue
 			}
+
+			flagNodes = append(flagNodes, p.parseConfiguredFlag(node, flCfg))
+
+			continue
 		}
 
 		flagNodes = append(flagNodes, node)
diff --git a/parser_error.go b/parser_error.go
new file mode 100644
index 0000000..62ae3b7
--- /dev/null
+++ b/parser_error.go
@@ -0,0 +1,88 @@
+package argh
+
+import (
+	"fmt"
+	"io"
+	"sort"
+)
+
+// ParserError is largely borrowed from go/scanner.Error
+type ParserError struct {
+	Pos Position
+	Msg string
+}
+
+func (e ParserError) Error() string {
+	if e.Pos.IsValid() {
+		return e.Pos.String() + ":" + e.Msg
+	}
+
+	return e.Msg
+}
+
+// ParserErrorList is largely borrowed from go/scanner.ErrorList
+type ParserErrorList []*ParserError
+
+func (el *ParserErrorList) Add(pos Position, msg string) {
+	*el = append(*el, &ParserError{Pos: pos, Msg: msg})
+}
+
+func (el *ParserErrorList) Reset() { *el = (*el)[0:0] }
+
+func (el ParserErrorList) Len() int { return len(el) }
+
+func (el ParserErrorList) Swap(i, j int) { el[i], el[j] = el[j], el[i] }
+
+func (el ParserErrorList) Less(i, j int) bool {
+	e := &el[i].Pos
+	f := &el[j].Pos
+
+	if e.Column != f.Column {
+		return e.Column < f.Column
+	}
+
+	return el[i].Msg < el[j].Msg
+}
+
+func (el ParserErrorList) Sort() {
+	sort.Sort(el)
+}
+
+func (el ParserErrorList) Error() string {
+	switch len(el) {
+	case 0:
+		return "no errors"
+	case 1:
+		return el[0].Error()
+	}
+	return fmt.Sprintf("%s (and %d more errors)", el[0], len(el)-1)
+}
+
+func (el ParserErrorList) Err() error {
+	if len(el) == 0 {
+		return nil
+	}
+	return el
+}
+
+func (el ParserErrorList) Is(other error) bool {
+	if _, ok := other.(ParserErrorList); ok {
+		return el.Error() == other.Error()
+	}
+
+	if v, ok := other.(*ParserErrorList); ok {
+		return el.Error() == (*v).Error()
+	}
+
+	return false
+}
+
+func PrintParserError(w io.Writer, err error) {
+	if list, ok := err.(ParserErrorList); ok {
+		for _, e := range list {
+			fmt.Fprintf(w, "%s\n", e)
+		}
+	} else if err != nil {
+		fmt.Fprintf(w, "%s\n", err)
+	}
+}
diff --git a/parser_test.go b/parser_test.go
index 0a4ad7c..fe57c77 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -25,6 +25,12 @@ func TestParser(t *testing.T) {
 			},
 			cfg: &argh.ParserConfig{
 				Prog: argh.CommandConfig{
+					Flags: map[string]argh.FlagConfig{
+						"e":   {},
+						"a":   {},
+						"t":   {},
+						"wat": {},
+					},
 					Commands: map[string]argh.CommandConfig{
 						"hello": argh.CommandConfig{
 							NValue:     1,
@@ -173,6 +179,15 @@ func TestParser(t *testing.T) {
 		{
 			name: "long value-less flags",
 			args: []string{"pizzas", "--tasty", "--fresh", "--super-hot-right-now"},
+			cfg: &argh.ParserConfig{
+				Prog: argh.CommandConfig{
+					Flags: map[string]argh.FlagConfig{
+						"tasty":               {},
+						"fresh":               {},
+						"super-hot-right-now": {},
+					},
+				},
+			},
 			expPT: []argh.Node{
 				&argh.Command{
 					Name: "pizzas",
@@ -211,8 +226,11 @@ func TestParser(t *testing.T) {
 				Prog: argh.CommandConfig{
 					Commands: map[string]argh.CommandConfig{},
 					Flags: map[string]argh.FlagConfig{
-						"fresh": argh.FlagConfig{NValue: 1},
-						"box":   argh.FlagConfig{NValue: argh.OneOrMoreValue},
+						"tasty":               {},
+						"fresh":               argh.FlagConfig{NValue: 1},
+						"super-hot-right-now": {},
+						"box":                 argh.FlagConfig{NValue: argh.OneOrMoreValue},
+						"please":              {},
 					},
 				},
 			},
@@ -281,6 +299,15 @@ func TestParser(t *testing.T) {
 		{
 			name: "short value-less flags",
 			args: []string{"pizzas", "-t", "-f", "-s"},
+			cfg: &argh.ParserConfig{
+				Prog: argh.CommandConfig{
+					Flags: map[string]argh.FlagConfig{
+						"t": {},
+						"f": {},
+						"s": {},
+					},
+				},
+			},
 			expPT: []argh.Node{
 				&argh.Command{
 					Name: "pizzas",
@@ -308,6 +335,17 @@ func TestParser(t *testing.T) {
 		{
 			name: "compound short flags",
 			args: []string{"pizzas", "-aca", "-blol"},
+			cfg: &argh.ParserConfig{
+				Prog: argh.CommandConfig{
+					Flags: map[string]argh.FlagConfig{
+						"a": {},
+						"b": {},
+						"c": {},
+						"l": {},
+						"o": {},
+					},
+				},
+			},
 			expPT: []argh.Node{
 				&argh.Command{
 					Name: "pizzas",
@@ -354,7 +392,11 @@ func TestParser(t *testing.T) {
 				Prog: argh.CommandConfig{
 					Commands: map[string]argh.CommandConfig{},
 					Flags: map[string]argh.FlagConfig{
-						"b": argh.FlagConfig{NValue: 1},
+						"a":  {},
+						"b":  argh.FlagConfig{NValue: 1},
+						"ca": {},
+						"l":  {},
+						"o":  {},
 					},
 				},
 			},
@@ -414,7 +456,11 @@ func TestParser(t *testing.T) {
 					Commands: map[string]argh.CommandConfig{
 						"fly": argh.CommandConfig{
 							Commands: map[string]argh.CommandConfig{
-								"fry": argh.CommandConfig{},
+								"fry": argh.CommandConfig{
+									Flags: map[string]argh.FlagConfig{
+										"forever": {},
+									},
+								},
 							},
 						},
 					},
@@ -689,7 +735,7 @@ func TestParser(t *testing.T) {
 						"w":       argh.FlagConfig{},
 						"A":       argh.FlagConfig{},
 						"T":       argh.FlagConfig{NValue: 1},
-						"hecking": argh.FlagConfig{},
+						"hecKing": argh.FlagConfig{},
 					},
 				},
 				ScannerConfig: &argh.ScannerConfig{
@@ -741,11 +787,61 @@ func TestParser(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "windows like",
+			args: []string{"hotdog", "/f", "/L", "/o:ppy", "hats"},
+			cfg: &argh.ParserConfig{
+				Prog: argh.CommandConfig{
+					Flags: map[string]argh.FlagConfig{
+						"f": {},
+						"L": {},
+						"o": argh.FlagConfig{NValue: 1},
+					},
+					Commands: map[string]argh.CommandConfig{
+						"hats": {},
+					},
+				},
+				ScannerConfig: &argh.ScannerConfig{
+					AssignmentOperator: ':',
+					FlagPrefix:         '/',
+					MultiValueDelim:    ',',
+				},
+			},
+			expPT: []argh.Node{
+				&argh.Command{
+					Name: "hotdog",
+					Nodes: []argh.Node{
+						&argh.ArgDelimiter{},
+						&argh.Flag{Name: "f"},
+						&argh.ArgDelimiter{},
+						&argh.Flag{Name: "L"},
+						&argh.ArgDelimiter{},
+						&argh.Flag{
+							Name:   "o",
+							Values: map[string]string{"0": "ppy"},
+							Nodes: []argh.Node{
+								&argh.Assign{},
+								&argh.Ident{Literal: "ppy"},
+							},
+						},
+						&argh.ArgDelimiter{},
+						&argh.Command{Name: "hats"},
+					},
+				},
+			},
+		},
 		{
 			name: "invalid bare assignment",
 			args: []string{"pizzas", "=", "--wat"},
-			expErr: argh.ScannerErrorList{
-				&argh.ScannerError{Pos: argh.Position{Column: 8}, Msg: "invalid bare assignment"},
+			cfg: &argh.ParserConfig{
+				Prog: argh.CommandConfig{
+					Flags: map[string]argh.FlagConfig{
+						"wat": {},
+					},
+				},
+			},
+			expErr: argh.ParserErrorList{
+				&argh.ParserError{Pos: argh.Position{Column: 8}, Msg: "invalid bare assignment"},
 			},
 			expPT: []argh.Node{
 				&argh.Command{
diff --git a/querier_test.go b/querier_test.go
index 06e2dae..bb3b767 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -16,8 +16,19 @@ func TestQuerier_Program(t *testing.T) {
 		expOK bool
 	}{
 		{
-			name:  "typical",
-			args:  []string{"pizzas", "ahoy", "--treatsa", "fun"},
+			name: "typical",
+			args: []string{"pizzas", "ahoy", "--treatsa", "fun"},
+			cfg: &argh.ParserConfig{
+				Prog: argh.CommandConfig{
+					Commands: map[string]argh.CommandConfig{
+						"ahoy": argh.CommandConfig{
+							Flags: map[string]argh.FlagConfig{
+								"treatsa": argh.FlagConfig{NValue: 1},
+							},
+						},
+					},
+				},
+			},
 			exp:   "pizzas",
 			expOK: true,
 		},
diff --git a/scanner_error.go b/scanner_error.go
deleted file mode 100644
index e5b634b..0000000
--- a/scanner_error.go
+++ /dev/null
@@ -1,88 +0,0 @@
-package argh
-
-import (
-	"fmt"
-	"io"
-	"sort"
-)
-
-// ScannerError is largely borrowed from go/scanner.Error
-type ScannerError struct {
-	Pos Position
-	Msg string
-}
-
-func (e ScannerError) Error() string {
-	if e.Pos.IsValid() {
-		return e.Pos.String() + ":" + e.Msg
-	}
-
-	return e.Msg
-}
-
-// ScannerErrorList is largely borrowed from go/scanner.ErrorList
-type ScannerErrorList []*ScannerError
-
-func (el *ScannerErrorList) Add(pos Position, msg string) {
-	*el = append(*el, &ScannerError{Pos: pos, Msg: msg})
-}
-
-func (el *ScannerErrorList) Reset() { *el = (*el)[0:0] }
-
-func (el ScannerErrorList) Len() int { return len(el) }
-
-func (el ScannerErrorList) Swap(i, j int) { el[i], el[j] = el[j], el[i] }
-
-func (el ScannerErrorList) Less(i, j int) bool {
-	e := &el[i].Pos
-	f := &el[j].Pos
-
-	if e.Column != f.Column {
-		return e.Column < f.Column
-	}
-
-	return el[i].Msg < el[j].Msg
-}
-
-func (el ScannerErrorList) Sort() {
-	sort.Sort(el)
-}
-
-func (el ScannerErrorList) Error() string {
-	switch len(el) {
-	case 0:
-		return "no errors"
-	case 1:
-		return el[0].Error()
-	}
-	return fmt.Sprintf("%s (and %d more errors)", el[0], len(el)-1)
-}
-
-func (el ScannerErrorList) Err() error {
-	if len(el) == 0 {
-		return nil
-	}
-	return el
-}
-
-func (el ScannerErrorList) Is(other error) bool {
-	if _, ok := other.(ScannerErrorList); ok {
-		return el.Error() == other.Error()
-	}
-
-	if v, ok := other.(*ScannerErrorList); ok {
-		return el.Error() == (*v).Error()
-	}
-
-	return false
-}
-
-func PrintScannerError(w io.Writer, err error) {
-	if list, ok := err.(ScannerErrorList); ok {
-		for _, e := range list {
-			fmt.Fprintf(w, "%s\n", e)
-		}
-	} else if err != nil {
-		fmt.Fprintf(w, "%s\n", err)
-	}
-}