diff --git a/src/json/parseany.cpp b/src/json/parseany.cpp
index b7119bd..7d1a2f6 100644
--- a/src/json/parseany.cpp
+++ b/src/json/parseany.cpp
@@ -15,6 +15,8 @@
 #include "pv/json.h"
 
 namespace pvd = epics::pvData;
+using pvd::yajl::integer_arg;
+using pvd::yajl::size_arg;
 
 namespace {
 
@@ -77,7 +79,7 @@ int jtree_boolean(void * ctx, int boolVal)
     }CATCH()
 }
 
-int jtree_integer(void * ctx, long integerVal)
+int jtree_integer(void * ctx, integer_arg integerVal)
 {
     TRY {
         if(self->depth==0) throw std::runtime_error("Bare value not supported");
@@ -130,7 +132,7 @@ int jtree_double(void * ctx, double doubleVal)
 }
 
 int jtree_string(void * ctx, const unsigned char * stringVal,
-                    unsigned int stringLen)
+                    size_arg stringLen)
 {
     TRY {
         if(self->depth==0) throw std::runtime_error("Bare value not supported");
@@ -172,7 +174,7 @@ int jtree_start_map(void * ctx)
 }
 
 int jtree_map_key(void * ctx, const unsigned char * key,
-                     unsigned int stringLen)
+                     size_arg stringLen)
 {
     TRY {
         if(!self->key.empty())
@@ -254,16 +256,24 @@ namespace epics{namespace pvData{
 epics::pvData::PVStructure::shared_pointer
 parseJSON(std::istream& strm)
 {
+#ifndef EPICS_YAJL_VERSION
     yajl_parser_config conf;
     memset(&conf, 0, sizeof(conf));
     conf.allowComments = 1;
     conf.checkUTF8 = 1;
+#endif
 
     context ctxt;
 
+#ifndef EPICS_YAJL_VERSION
     handler handle(yajl_alloc(&jtree_cbs, &conf, NULL, &ctxt));
+#else
+    handler handle(yajl_alloc(&jtree_cbs, NULL, &ctxt));
 
-    if(!yajl_parse_helper(strm, handle, conf))
+    yajl_config(handle, yajl_allow_comments, 1);
+#endif
+
+    if(!yajl_parse_helper(strm, handle))
         throw std::runtime_error(ctxt.msg);
 
     return ctxt.cur->buildPVStructure();
diff --git a/src/json/parsehelper.cpp b/src/json/parsehelper.cpp
index 34ed895..bd53db0 100644
--- a/src/json/parsehelper.cpp
+++ b/src/json/parsehelper.cpp
@@ -15,7 +15,7 @@
 
 namespace {
 
-void check_trailing(const std::string& line, bool commentok)
+void check_trailing(const std::string& line)
 {
     size_t idx = line.find_first_not_of(" \t\n\r");
     if(idx==line.npos) return;
@@ -29,37 +29,46 @@ void check_trailing(const std::string& line, bool commentok)
 namespace epics{namespace pvData{
 
 bool yajl_parse_helper(std::istream& src,
-                       yajl_handle handle,
-                       const yajl_parser_config& config)
+                       yajl_handle handle)
 {
     unsigned linenum=0;
+#ifndef EPICS_YAJL_VERSION
     bool done = false;
+#endif
 
     std::string line;
     while(std::getline(src, line)) {
         linenum++;
 
+#ifndef EPICS_YAJL_VERSION
         if(done) {
-            check_trailing(line, config.allowComments);
+            check_trailing(line);
             continue;
         }
+#endif
 
         yajl_status sts = yajl_parse(handle, (const unsigned char*)line.c_str(), line.size());
 
         switch(sts) {
         case yajl_status_ok: {
             size_t consumed = yajl_get_bytes_consumed(handle);
+
             if(consumed<line.size()) {
-                check_trailing(line.substr(consumed), config.allowComments);
+                check_trailing(line.substr(consumed));
             }
+
+#ifndef EPICS_YAJL_VERSION
             done = true;
+#endif
             break;
         }
         case yajl_status_client_canceled:
             return false;
+#ifndef EPICS_YAJL_VERSION
         case yajl_status_insufficient_data:
             // continue with next line
             break;
+#endif
         case yajl_status_error:
         {
             std::ostringstream msg;
@@ -85,15 +94,24 @@ bool yajl_parse_helper(std::istream& src,
         msg<<"I/O error after line "<<linenum;
         throw std::runtime_error(msg.str());
 
-    } else if(!done) switch(yajl_parse_complete(handle)) {
-    case yajl_status_ok:
-        break;
-    case yajl_status_client_canceled:
-        return false;
-    case yajl_status_insufficient_data:
-        throw std::runtime_error("unexpected end of input");
-    case yajl_status_error:
-        throw std::runtime_error("Error while completing parsing");
+#ifndef EPICS_YAJL_VERSION
+    } else if(!done) {
+        switch(yajl_parse_complete(handle)) {
+#else
+    } else {
+        switch(yajl_complete_parse(handle)) {
+#endif
+        case yajl_status_ok:
+            break;
+        case yajl_status_client_canceled:
+            return false;
+#ifndef EPICS_YAJL_VERSION
+        case yajl_status_insufficient_data:
+            throw std::runtime_error("unexpected end of input");
+#endif
+        case yajl_status_error:
+            throw std::runtime_error("Error while completing parsing");
+        }
     }
 
     return true;
diff --git a/src/json/parseinto.cpp b/src/json/parseinto.cpp
index e433cc3..940f6c3 100644
--- a/src/json/parseinto.cpp
+++ b/src/json/parseinto.cpp
@@ -17,6 +17,8 @@
 #include "pv/json.h"
 
 namespace pvd = epics::pvData;
+using pvd::yajl::integer_arg;
+using pvd::yajl::size_arg;
 
 namespace {
 struct context {
@@ -148,7 +150,7 @@ int jtree_boolean(void * ctx, int boolVal)
     }CATCH()
 }
 
-int jtree_integer(void * ctx, long integerVal)
+int jtree_integer(void * ctx, integer_arg integerVal)
 {
     TRY {
         valueAssign<pvd::PVLong, pvd::PVLongArray>(self, integerVal);
@@ -165,7 +167,7 @@ int jtree_double(void * ctx, double doubleVal)
 }
 
 int jtree_string(void * ctx, const unsigned char * stringVal,
-                    unsigned int stringLen)
+                    size_arg stringLen)
 {
     TRY {
         std::string val((const char*)stringVal, stringLen);
@@ -200,7 +202,7 @@ int jtree_start_map(void * ctx)
 }
 
 int jtree_map_key(void * ctx, const unsigned char * key,
-                     unsigned int stringLen)
+                     size_arg stringLen)
 {
     TRY {
         assert(!self->stack.empty());
@@ -309,16 +311,25 @@ void parseJSON(std::istream& strm,
                const PVField::shared_pointer& dest,
                BitSet *assigned)
 {
+#ifndef EPICS_YAJL_VERSION
     yajl_parser_config conf;
     memset(&conf, 0, sizeof(conf));
     conf.allowComments = 1;
     conf.checkUTF8 = 1;
+#endif
 
     context ctxt(dest, assigned);
 
+#ifndef EPICS_YAJL_VERSION
     handler handle(yajl_alloc(&jtree_cbs, &conf, NULL, &ctxt));
+#else
+    handler handle(yajl_alloc(&jtree_cbs, NULL, &ctxt));
 
-    if(!yajl_parse_helper(strm, handle, conf))
+    yajl_config(handle, yajl_allow_comments, 1);
+#endif
+
+
+    if(!yajl_parse_helper(strm, handle))
         throw std::runtime_error(ctxt.msg);
 
     if(!ctxt.stack.empty())
diff --git a/src/json/pv/json.h b/src/json/pv/json.h
index 5455fe8..5a7bc19 100644
--- a/src/json/pv/json.h
+++ b/src/json/pv/json.h
@@ -96,14 +96,25 @@ void parseJSON(std::istream& strm,
  *
  * @param src The stream from which input charactors are read
  * @param handle A parser handle previously allocated with yajl_alloc().  Not free'd on success or failure.
- * @param config The same configuration passed to yajl_alloc().  Used to decide if trailing comments are allowed
  *
  * @returns true if parsing completes successfully.  false if parsing cancelled by callback.  throws other errors
+ *
+ * @note The form of this call depends on EPICS_YAJL_VERSION
  */
 epicsShareFunc
 bool yajl_parse_helper(std::istream& src,
-                       yajl_handle handle,
-                       const yajl_parser_config& config);
+                       yajl_handle handle);
+
+namespace yajl {
+// undef implies API version 0
+#ifndef EPICS_YAJL_VERSION
+typedef long integer_arg;
+typedef unsigned size_arg;
+#else
+typedef long long integer_arg;
+typedef size_t size_arg;
+#endif
+} // namespace epics::pvData::yajl
 
 /** @} */
 
diff --git a/testApp/misc/testjson.cpp b/testApp/misc/testjson.cpp
index afa9eef..f156a25 100644
--- a/testApp/misc/testjson.cpp
+++ b/testApp/misc/testjson.cpp
@@ -97,12 +97,16 @@ void testparseanyjunk()
     {
         testThrows(std::runtime_error, std::istringstream strm("{} x"); std::cout<<pvd::parseJSON(strm) );
     }
+#ifndef EPICS_YAJL_VERSION
     {
         testThrows(std::runtime_error, std::istringstream strm("{} /* y */"); std::cout<<pvd::parseJSON(strm) );
     }
     {
         testThrows(std::runtime_error, std::istringstream strm("{} /* y *"); std::cout<<pvd::parseJSON(strm) );
     }
+#else
+    testSkip(2, "yajl >= 2.1.0 handles trailing comments for us");
+#endif
     {
         testThrows(std::runtime_error, std::istringstream strm("{}\n\n{}"); std::cout<<pvd::parseJSON(strm) );
     }