diff --git a/json.applescript b/json.applescript
index 97fa183..972e677 100644
--- a/json.applescript
+++ b/json.applescript
@@ -25,15 +25,22 @@ end
 
 on encodeString(value)
 	set rv to ""
-	repeat with ch in value
-		if id of ch = 34
+	set codepoints to id of value
+
+	if (class of codepoints) is not list
+		set codepoints to {codepoints}
+	end
+
+	repeat with codepoint in codepoints
+		set codepoint to codepoint as integer
+		if codepoint = 34
 			set quoted_ch to "\\\""
-		else if id of ch = 92 then
+		else if codepoint = 92 then
 			set quoted_ch to "\\\\"
-		else if id of ch >= 32 and id of ch < 127
-			set quoted_ch to ch
+		else if codepoint >= 32 and codepoint < 127
+			set quoted_ch to character id codepoint
 		else
-			set quoted_ch to "\\u" & hex4(id of ch)
+			set quoted_ch to "\\u" & hex4(codepoint)
 		end
 		set rv to rv & quoted_ch
 	end
diff --git a/tests.applescript b/tests.applescript
index 6a23d4f..7fbdf7e 100644
--- a/tests.applescript
+++ b/tests.applescript
@@ -32,6 +32,7 @@ assert_eq(json's encode("foo"), "\"foo\"")
 assert_eq(json's encode(""), "\"\"")
 assert_eq(json's encode("\n"), "\"\\u000a\"")
 assert_eq(json's encode("ș"), "\"\\u0219\"")
+assert_eq(json's encode("u" & "̈"), "\"u\\u0308\"")
 assert_eq(json's encode("\"bar\""), "\"\\\"bar\\\"\"")
 assert_eq(json's encode("\\"), "\"\\\\\"")