diff --git a/hclsyntax/token.go b/hclsyntax/token.go
index 5964475..59f4c43 100644
--- a/hclsyntax/token.go
+++ b/hclsyntax/token.go
@@ -294,12 +294,23 @@ func checkInvalidTokens(tokens Tokens) hcl.Diagnostics {
 				Subject:  &tok.Range,
 			})
 		case TokenInvalid:
-			diags = append(diags, &hcl.Diagnostic{
-				Severity: hcl.DiagError,
-				Summary:  "Invalid character",
-				Detail:   "This character is not used within the language.",
-				Subject:  &tok.Range,
-			})
+			chars := string(tok.Bytes)
+			switch chars {
+			case "“", "”":
+				diags = append(diags, &hcl.Diagnostic{
+					Severity: hcl.DiagError,
+					Summary:  "Invalid character",
+					Detail:   "\"Curly quotes\" are not valid here. These can sometimes be inadvertently introduced when sharing code via documents or discussion forums. It might help to replace the character with a \"straight quote\".",
+					Subject:  &tok.Range,
+				})
+			default:
+				diags = append(diags, &hcl.Diagnostic{
+					Severity: hcl.DiagError,
+					Summary:  "Invalid character",
+					Detail:   "This character is not used within the language.",
+					Subject:  &tok.Range,
+				})
+			}
 		}
 	}
 	return diags
diff --git a/hclsyntax/token_test.go b/hclsyntax/token_test.go
new file mode 100644
index 0000000..a954d60
--- /dev/null
+++ b/hclsyntax/token_test.go
@@ -0,0 +1,60 @@
+package hclsyntax
+
+import (
+	"testing"
+
+	"github.com/hashicorp/hcl/v2"
+)
+
+func TestCheckInvalidTokensTest(t *testing.T) {
+	tests := []struct {
+		Input       string
+		WantSummary string
+		WantDetail  string
+	}{
+		{
+			`block “invalid” {}`,
+			`Invalid character`,
+			`"Curly quotes" are not valid here. These can sometimes be inadvertently introduced when sharing code via documents or discussion forums. It might help to replace the character with a "straight quote".`,
+		},
+		{
+			`block 'invalid' {}`,
+			`Invalid character`,
+			`Single quotes are not valid. Use double quotes (") to enclose strings.`,
+		},
+		{
+			"block `invalid` {}",
+			`Invalid character`,
+			"The \"`\" character is not valid. To create a multi-line string, use the \"heredoc\" syntax, like \"<<EOT\".",
+		},
+		{
+			`foo = a & b`,
+			`Unsupported operator`,
+			`Bitwise operators are not supported. Did you mean boolean AND ("&&")?`,
+		},
+		{
+			`foo = a | b`,
+			`Unsupported operator`,
+			`Bitwise operators are not supported. Did you mean boolean OR ("||")?`,
+		},
+		{
+			`foo = ~a`,
+			`Unsupported operator`,
+			`Bitwise operators are not supported. Did you mean boolean NOT ("!")?`,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Input, func(t *testing.T) {
+			_, diags := LexConfig([]byte(test.Input), "", hcl.Pos{Line: 1, Column: 1})
+			for _, diag := range diags {
+				if diag.Severity == hcl.DiagError && diag.Summary == test.WantSummary && diag.Detail == test.WantDetail {
+					return // success!
+				}
+			}
+			// If we fall out here then we didn't find the diagnostic we were
+			// looking for.
+			t.Errorf("wrong errors\ngot:  %s\nwant: %s; %s", diags.Error(), test.WantSummary, test.WantDetail)
+		})
+	}
+}