diff --git a/src/msw/webrequest_winhttp.cpp b/src/msw/webrequest_winhttp.cpp
index d31c12ef05..3608b1483b 100644
--- a/src/msw/webrequest_winhttp.cpp
+++ b/src/msw/webrequest_winhttp.cpp
@@ -152,7 +152,15 @@ static wxString wxWinHTTPQueryHeaderString(HINTERNET hRequest, DWORD dwInfoLevel
         WINHTTP_NO_HEADER_INDEX);
     if ( ::GetLastError() == ERROR_INSUFFICIENT_BUFFER )
     {
-        wxWCharBuffer resBuf(bufferLen);
+        // Buffer length is in bytes, including the terminating (wide) NUL, but
+        // wxWCharBuffer needs the size in characters and adds NUL itself.
+        if ( !bufferLen || (bufferLen % sizeof(wchar_t)) )
+        {
+            wxLogDebug("Unexpected size of header %s: %lu", pwszName, bufferLen);
+            return wxString();
+        }
+
+        wxWCharBuffer resBuf(bufferLen / sizeof(wchar_t) - 1);
         if ( wxWinHTTP::WinHttpQueryHeaders(hRequest, dwInfoLevel, pwszName,
                                    resBuf.data(), &bufferLen,
                                    WINHTTP_NO_HEADER_INDEX) )
@@ -171,7 +179,14 @@ static wxString wxWinHTTPQueryOptionString(HINTERNET hInternet, DWORD dwOption)
     wxWinHTTP::WinHttpQueryOption(hInternet, dwOption, NULL, &bufferLen);
     if ( ::GetLastError() == ERROR_INSUFFICIENT_BUFFER )
     {
-        wxWCharBuffer resBuf(bufferLen);
+        // Same as above: convert length in bytes into size in characters.
+        if ( !bufferLen || (bufferLen % sizeof(wchar_t)) )
+        {
+            wxLogDebug("Unexpected size of option %lu: %lu", dwOption, bufferLen);
+            return wxString();
+        }
+
+        wxWCharBuffer resBuf(bufferLen / sizeof(wchar_t) - 1);
         if ( wxWinHTTP::WinHttpQueryOption(hInternet, dwOption, resBuf.data(), &bufferLen) )
             result.assign(resBuf);
     }
diff --git a/tests/net/webrequest.cpp b/tests/net/webrequest.cpp
index 14593422ee..6b6e4eef69 100644
--- a/tests/net/webrequest.cpp
+++ b/tests/net/webrequest.cpp
@@ -229,6 +229,17 @@ TEST_CASE_METHOD(RequestFixture,
     CHECK( request.GetResponse().AsString() == "The quick brown fox jumps over the lazy dog" );
 }
 
+TEST_CASE_METHOD(RequestFixture,
+                 "WebRequest::Get::Header", "[net][webrequest][get]")
+{
+    if ( !InitBaseURL() )
+        return;
+
+    Create("/response-headers?freeform=wxWidgets%20works!");
+    Run();
+    CHECK( request.GetResponse().GetHeader("freeform") == "wxWidgets works!" );
+}
+
 TEST_CASE_METHOD(RequestFixture,
                  "WebRequest::Get::Param", "[net][webrequest][get]")
 {
@@ -510,13 +521,21 @@ TEST_CASE_METHOD(RequestFixture,
     request.Start();
     RunLoopWithTimeout();
 
-    WARN("Request state " << request.GetState());
+    CHECK( request.GetState() == wxWebRequest::State_Completed );
     wxWebResponse response = request.GetResponse();
     REQUIRE( response.IsOk() );
-    WARN("Status: " << response.GetStatus()
+    WARN("URL: " << response.GetURL() << "\n" <<
+         "Status: " << response.GetStatus()
                     << " (" << response.GetStatusText() << ")\n" <<
          "Body length: " << response.GetContentLength() << "\n" <<
          "Body: " << response.AsString() << "\n");
+
+    // Also show the value of the given header if requested.
+    wxString header;
+    if ( wxGetEnv("WX_TEST_WEBREQUEST_HEADER", &header) )
+    {
+        WARN("Header " << header << ": " << response.GetHeader(header));
+    }
 }
 
 WX_DECLARE_STRING_HASH_MAP(wxString, wxWebRequestHeaderMap);