diff --git a/cmd/participle/gen_lexer_cmd.go b/cmd/participle/gen_lexer_cmd.go
index 97f83647..edc0fdcc 100644
--- a/cmd/participle/gen_lexer_cmd.go
+++ b/cmd/participle/gen_lexer_cmd.go
@@ -292,18 +292,15 @@ func generateRegexMatch(w io.Writer, lexerName, name, pattern string) error {
 			syntax.OpBeginText, syntax.OpEndText,
 			syntax.OpBeginLine, syntax.OpEndLine:
 			fmt.Fprintf(w, "var l, u rune = -1, -1\n")
-			fmt.Fprintf(w, "var checkPrevChar = false\n")
 			fmt.Fprintf(w, "if p == 0 {\n")
+			fmt.Fprintf(w, "  if p < len(s) {\n")
 			decodeRune(w, "0", "u", "_")
+			fmt.Fprintf(w, "  }\n")
 			fmt.Fprintf(w, "} else if p == len(s) {\n")
 			fmt.Fprintf(w, "  l, _ = utf8.DecodeLastRuneInString(s)\n")
 			fmt.Fprintf(w, "} else {\n")
-			fmt.Fprintf(w, "  checkPrevChar = true\n")
-			fmt.Fprintf(w, "  var ln int\n")
-			decodeRune(w, "p", "l", "ln")
-			fmt.Fprintf(w, "  if p+ln <= len(s) {\n")
-			decodeRune(w, "p+ln", "u", "_")
-			fmt.Fprintf(w, "  }\n")
+			fmt.Fprintf(w, "  l, _ = utf8.DecodeLastRuneInString(s[0:p])\n")
+			decodeRune(w, "p", "u", "_")
 			fmt.Fprintf(w, "}\n")
 			fmt.Fprintf(w, "op := syntax.EmptyOpContext(l, u)\n")
 			lut := map[syntax.Op]string{
@@ -315,16 +312,6 @@ func generateRegexMatch(w io.Writer, lexerName, name, pattern string) error {
 				syntax.OpEndLine:        "EmptyEndLine",
 			}
 			fmt.Fprintf(w, "if op & syntax.%s != 0 { return p }\n", lut[re.Op])
-			// If this isn't the start or end of the string, we also have to check if we match
-			// the preceding character (zero length op could have matched right before)
-			fmt.Fprintf(w, "if checkPrevChar {\n")
-			// decode the character immediately previous to this one (conditional logic above
-			// guarantees that p is > 0)
-			fmt.Fprintf(w, "  l, _ = utf8.DecodeLastRuneInString(s[0:p])\n")
-			decodeRune(w, "p", "u", "_")
-			fmt.Fprintf(w, "  op := syntax.EmptyOpContext(l, u)\n")
-			fmt.Fprintf(w, "  if op & syntax.%s != 0 { return p }\n", lut[re.Op])
-			fmt.Fprintf(w, "}\n")
 			fmt.Fprintf(w, "return -1\n")
 
 		case syntax.OpCapture: // capturing subexpression with index Cap, optional name Name
diff --git a/lexer/internal/conformance/conformance_test.go b/lexer/internal/conformance/conformance_test.go
index c39a7521..839bbc1d 100644
--- a/lexer/internal/conformance/conformance_test.go
+++ b/lexer/internal/conformance/conformance_test.go
@@ -19,7 +19,8 @@ var conformanceLexer = lexer.MustStateful(lexer.Rules{
 		{"ExprTest", `EXPRTEST:`, lexer.Push("ExprTest")},
 		{"LiteralTest", `LITTEST:`, lexer.Push("LiteralTest")},
 		{"CaseInsensitiveTest", `CITEST:`, lexer.Push("CaseInsensitiveTest")},
-		{"WordBoundaryTest", `WBTEST:`, lexer.Push("WordBoundaryTest")},
+		// Use this to test \b at very start of the string!
+		{"WordBoundaryTest", `\bWBTEST:`, lexer.Push("WordBoundaryTest")},
 	},
 	"ExprTest": {
 		{"ExprString", `"`, lexer.Push("ExprString")},
@@ -61,6 +62,7 @@ var conformanceLexer = lexer.MustStateful(lexer.Rules{
 	},
 	"WordBoundaryTest": {
 		{`WBKeyword`, `\b(?:abc|xyz)\b`, nil},
+		{`WBGroupKeyword`, `(?:90|0)\b`, nil},
 		{"Slash", `/`, nil},
 		{"Ident", `\w+`, nil},
 		{"Whitespace", `\s+`, nil},
@@ -160,6 +162,11 @@ func testLexer(t *testing.T, lex lexer.Definition) {
 			{"Whitespace", " "},
 			{"Ident", "world"},
 		}},
+		{"WordBoundarySlash2", `WBTEST:abc/xyz`, []token{
+			{"WBKeyword", "abc"},
+			{"Slash", "/"},
+			{"WBKeyword", "xyz"},
+		}},
 		{"WordBoundaryWhitespace", `WBTEST:abchello xyz world`, []token{
 			{"Ident", "abchello"},
 			{"Whitespace", " "},
@@ -167,9 +174,36 @@ func testLexer(t *testing.T, lex lexer.Definition) {
 			{"Whitespace", " "},
 			{"Ident", "world"},
 		}},
+		// Case to ensure \b doesn't match even if only one character after token would match \b
+		{"WordBoundaryNoMatch1", `WBTEST:abc1 xyz1`, []token{
+			{"Ident", "abc1"},
+			{"Whitespace", " "},
+			{"Ident", "xyz1"},
+		}},
+		{"WordBoundaryNoMatch2", `WBTEST:abc12 xyz12`, []token{
+			{"Ident", "abc12"},
+			{"Whitespace", " "},
+			{"Ident", "xyz12"},
+		}},
 		{"WordBoundaryStartEnd", `WBTEST:xyz`, []token{
 			{"WBKeyword", "xyz"},
 		}},
+		{"WordBoundaryGroupMatch", `WBTEST:hello 90/0 world`, []token{
+			{"Ident", "hello"},
+			{"Whitespace", " "},
+			{"WBGroupKeyword", "90"},
+			{"Slash", "/"},
+			{"WBGroupKeyword", "0"},
+			{"Whitespace", " "},
+			{"Ident", "world"},
+		}},
+		{"WordBoundaryGroupNoMatch", `WBTEST:hello 900 world`, []token{
+			{"Ident", "hello"},
+			{"Whitespace", " "},
+			{"Ident", "900"},
+			{"Whitespace", " "},
+			{"Ident", "world"},
+		}},
 	}
 	symbols := lexer.SymbolsByRune(lex)
 	for _, test := range tests {