diff --git a/api/tesseractmain.cpp b/api/tesseractmain.cpp
index dc9fabf8581663d513b9913717ddad4de167d839..2d18e432433647139cdedb7a1462245af0e74d2a 100644
--- a/api/tesseractmain.cpp
+++ b/api/tesseractmain.cpp
@@ -50,6 +50,29 @@ int main(int argc, char **argv) {
     fprintf(stderr, "  %s\n", versionStrP);
     lept_free(versionStrP);
 
+#ifdef USE_OPENCL
+    cl_platform_id platform;
+    cl_uint num_platforms;
+    cl_device_id devices[2];
+    cl_uint num_devices;
+    cl_int err;
+    char info[256];
+    int i;
+
+    fprintf(stderr, " OpenCL info:\n");
+    clGetPlatformIDs(1, &platform, &num_platforms);
+    fprintf(stderr, "  Found %d platforms.\n", num_platforms);
+    clGetPlatformInfo(platform, CL_PLATFORM_NAME, 256, info, 0);
+    fprintf(stderr, "  Platform name: %s.\n", info);
+    clGetPlatformInfo(platform, CL_PLATFORM_VERSION, 256, info, 0);
+    fprintf(stderr, "  Version: %s.\n", info);
+    clGetDeviceIDs(platform, CL_DEVICE_TYPE_ALL, 2, devices, &num_devices);
+    fprintf(stderr, "  Found %d devices.\n", num_devices);
+    for (i = 0; i < num_devices; ++i) {
+      clGetDeviceInfo(devices[i], CL_DEVICE_NAME, 256, info, 0);
+      fprintf(stderr, "    Device %d name: %s.\n", i+1, info);
+    }
+#endif
     exit(0);
   }
 
@@ -194,7 +217,6 @@ int main(int argc, char **argv) {
   tprintf("Tesseract Open Source OCR Engine v%s with Leptonica\n",
            tesseract::TessBaseAPI::Version());
 
-
   FILE* fin = fopen(image, "rb");
   if (fin == NULL) {
     fprintf(stderr, "Cannot open input file: %s\n", image);
diff --git a/configure.ac b/configure.ac
index 13ddf9f891cf3bc66e7af2cca438d6420210ce29..6c7d33178a5968fb2fd88f31bcd98410878885b0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -57,8 +57,8 @@ AC_SUBST(GENERIC_VERSION)
 AM_CONDITIONAL(MINGW, false)
 AM_CONDITIONAL(GRAPHICS_DISABLED, false)
 
-OPENCL_HDR_PATH=""
-OPENCL_LIB=""
+OPENCL_INC="/opt/AMDAPP/include"
+OPENCL_LIBS="-lOpenCL"
 #############################
 #
 # Platform specific setup
@@ -74,6 +74,14 @@ case "${host_os}" in
     solaris*)
         LIBS="-lsocket -lnsl -lrt -lxnet"
         ;;
+    powerpc-*-darwin*)
+        OPENCL_LIBS=""
+        OPENCL_INC=""
+        ;;
+    *-*-darwin*)
+        OPENCL_LIBS="-framework OpenCL"
+        OPENCL_INC=""
+        ;;
      *)
         # default
         ;;
@@ -126,15 +134,15 @@ fi
 # check whether to build opencl version
 AC_MSG_CHECKING(--enable-opencl argument)
 AC_ARG_ENABLE([opencl],
-    [  --enable-opencl       enable opencl build (default=no)],
+    [  --enable-opencl         enable opencl build (default=no)],
     [enable_opencl=$enableval],
     [enable_opencl="no"])
 AC_MSG_RESULT($enable_opencl)
 AM_CONDITIONAL([USE_OPENCL], [test "$enable_opencl" = "yes"])
 if test "$enable_opencl" = "yes"; then
   AC_SUBST([AM_CPPFLAGS], [-DUSE_OPENCL])
-  AC_SUBST([OPENCL_HDR_PATH],["/opt/AMDAPP/include"])
-  AC_SUBST([OPENCL_LIB],["-lOpenCL"])
+  AC_SUBST([OPENCL_HDR_PATH],[$OPENCL_INC])
+  AC_SUBST([OPENCL_LIB],[$OPENCL_LIBS])
 fi
 
 # check whether to build tesseract with -fvisibility=hidden -fvisibility-inlines-hidden
diff --git a/opencl/opencl_device_selection.h b/opencl/opencl_device_selection.h
index d28f2a278ee399a25853967e72c462804f77ceb6..64e317fff522a59fd28037cf9342177f063652c8 100644
--- a/opencl/opencl_device_selection.h
+++ b/opencl/opencl_device_selection.h
@@ -11,7 +11,12 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+
+#ifdef __APPLE__
+#include <OpenCL/cl.h>
+#else
 #include <CL/cl.h>
+#endif
 
 #define DS_DEVICE_NAME_LENGTH 256
 
diff --git a/opencl/openclwrapper.cpp b/opencl/openclwrapper.cpp
index d103b7d858c192e57dd226cca4ae20fc2a8f1876..1b5ccfe0a5fb66ef07552a4bd3e301a67a5f052d 100644
--- a/opencl/openclwrapper.cpp
+++ b/opencl/openclwrapper.cpp
@@ -2518,8 +2518,8 @@ PERF_COUNT_START("ThresholdRectToPixOCL")
     int requestedOccupancy = 10;
     int numWorkGroups = numCUs * requestedOccupancy;
     int numThreads = block_size*numWorkGroups;
-    size_t local_work_size[] = {block_size};
-    size_t global_work_size[] = {numThreads};
+    size_t local_work_size[] = {(size_t) block_size};
+    size_t global_work_size[] = {(size_t) numThreads};
 
     /* map imagedata to device as read only */
     // USE_HOST_PTR uses onion+ bus which is slowest option; also happens to be coherent which we don't need.
diff --git a/opencl/openclwrapper.h b/opencl/openclwrapper.h
index e0425e9cc375d52b7b8043a8874ec35c91a856fb..976f070133e0cafc02e95392860f6420ccd15a27 100644
--- a/opencl/openclwrapper.h
+++ b/opencl/openclwrapper.h
@@ -138,7 +138,6 @@
 
 #define USE_DEVICE_SELECTION 1
 
-#include "CL/cl.h"
 #include "opencl_device_selection.h"
 
 #ifndef strcasecmp