diff --git a/src/go/scanner/scanner.go b/src/go/scanner/scanner.go
index 75f835d3105..8742c299065 100644
--- a/src/go/scanner/scanner.go
+++ b/src/go/scanner/scanner.go
@@ -943,7 +943,13 @@ scanAgain:
 		default:
 			// next reports unexpected BOMs - don't repeat
 			if ch != bom {
-				s.errorf(s.file.Offset(pos), "illegal character %#U", ch)
+				// Report an informative error for U+201[CD] quotation
+				// marks, which are easily introduced via copy and paste.
+				if ch == '“' || ch == '”' {
+					s.errorf(s.file.Offset(pos), "curly quotation mark %q (use neutral %q)", ch, '"')
+				} else {
+					s.errorf(s.file.Offset(pos), "illegal character %#U", ch)
+				}
 			}
 			insertSemi = s.insertSemi // preserve insertSemi info
 			tok = token.ILLEGAL
diff --git a/src/go/scanner/scanner_test.go b/src/go/scanner/scanner_test.go
index 9046148ac2c..916a40a8744 100644
--- a/src/go/scanner/scanner_test.go
+++ b/src/go/scanner/scanner_test.go
@@ -813,6 +813,7 @@ var errors = []struct {
 	{`"` + "abc\ufeffdef" + `"`, token.STRING, 4, `"` + "abc\ufeffdef" + `"`, "illegal byte order mark"}, // only first BOM is ignored
 	{"abc\x00def", token.IDENT, 3, "abc", "illegal character NUL"},
 	{"abc\x00", token.IDENT, 3, "abc", "illegal character NUL"},
+	{"“abc”", token.ILLEGAL, 0, "abc", `curly quotation mark '“' (use neutral '"')`},
 }
 
 func TestScanErrors(t *testing.T) {