diff --git a/src/tool_writeout_json.c b/src/tool_writeout_json.c
index 7bc74a2697..4ed6b93fb7 100644
--- a/src/tool_writeout_json.c
+++ b/src/tool_writeout_json.c
@@ -41,8 +41,8 @@
 int jsonquoted(const char *in, size_t len,
                struct curlx_dynbuf *out, bool lowercase)
 {
-  const char *i = in;
-  const char *in_end = &in[len];
+  const unsigned char *i = (unsigned char *)in;
+  const unsigned char *in_end = &i[len];
   CURLcode result = CURLE_OK;
 
   for(; (i < in_end) && !result; i++) {
diff --git a/tests/data/Makefile.inc b/tests/data/Makefile.inc
index 2608e16d6e..de13c525e8 100644
--- a/tests/data/Makefile.inc
+++ b/tests/data/Makefile.inc
@@ -51,7 +51,7 @@ test226 test227 test228 test229 test230 test231 test232 test233 test234 \
 test235 test236 test237 test238 test239 test240 test241 test242 test243 \
 test244 test245 test246 test247 test248 test249 test250 test251 test252 \
 test253 test254 test255 test256 test257 test258 test259 test260 test261 \
-test262 test263 test264 test265 test266 test267 test269 test270 \
+test262 test263 test264 test265 test266 test267 test268 test269 test270 \
 test271 test272 test273 test274 test275 test276 test277 test278 test279 \
 test280 test281 test282 test283 test284 test285 test286 test287 test288 \
 test289 test290 test291 test292 test293 test294 test295 test296 test297 \
diff --git a/tests/data/test268 b/tests/data/test268
new file mode 100644
index 0000000000..3a1ab6a9b5
--- /dev/null
+++ b/tests/data/test268
@@ -0,0 +1,59 @@
+<testcase>
+<info>
+<keywords>
+HTTP
+variables
+</keywords>
+</info>
+
+#
+# Server-side
+<reply>
+<data crlf="yes">
+HTTP/1.1 200 OK
+Date: Tue, 09 Nov 2010 14:49:00 GMT
+Server: test-server/fake
+Last-Modified: Tue, 13 Jun 2000 12:10:00 GMT
+ETag: "21025-dc7-39462498"
+Accept-Ranges: bytes
+Content-Length: 6
+Connection: close
+Content-Type: text/html
+Funny-head: yesyes
+
+-foo-
+</data>
+</reply>
+
+#
+# Client-side
+<client>
+<server>
+http
+</server>
+<name>
+JSON encoding of unicode string
+</name>
+<file name="%LOGDIR/junk" nonewline="yes">
+%hex[%e2%80%9c]hex%
+</file>
+<command>
+http://%HOSTIP:%HTTPPORT/%TESTNUMBER --variable hello@%LOGDIR/junk --expand-data {{hello:json}}
+</command>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+<protocol crlf="yes" nonewline="yes">
+POST /%TESTNUMBER HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+User-Agent: curl/%VERSION
+Accept: */*
+Content-Length: 3
+Content-Type: application/x-www-form-urlencoded
+
+%hex[%e2%80%9c]hex%
+</protocol>
+</verify>
+</testcase>