diff --git a/src/unicode/letter.go b/src/unicode/letter.go
index 90b0b414da297..4d9fc67165cf8 100644
--- a/src/unicode/letter.go
+++ b/src/unicode/letter.go
@@ -97,7 +97,7 @@ func is16(ranges []Range16, r uint16) bool {
 				return false
 			}
 			if r <= range_.Hi {
-				return (r-range_.Lo)%range_.Stride == 0
+				return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
 			}
 		}
 		return false
@@ -110,7 +110,7 @@ func is16(ranges []Range16, r uint16) bool {
 		m := lo + (hi-lo)/2
 		range_ := &ranges[m]
 		if range_.Lo <= r && r <= range_.Hi {
-			return (r-range_.Lo)%range_.Stride == 0
+			return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
 		}
 		if r < range_.Lo {
 			hi = m
@@ -130,7 +130,7 @@ func is32(ranges []Range32, r uint32) bool {
 				return false
 			}
 			if r <= range_.Hi {
-				return (r-range_.Lo)%range_.Stride == 0
+				return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
 			}
 		}
 		return false
@@ -143,7 +143,7 @@ func is32(ranges []Range32, r uint32) bool {
 		m := lo + (hi-lo)/2
 		range_ := ranges[m]
 		if range_.Lo <= r && r <= range_.Hi {
-			return (r-range_.Lo)%range_.Stride == 0
+			return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
 		}
 		if r < range_.Lo {
 			hi = m