diff --git a/Makefile b/Makefile
index 1925282..b354dac 100644
--- a/Makefile
+++ b/Makefile
@@ -215,9 +215,40 @@ uninstall:
 	rm -rf $(INSTALLED_LIBS) $(INSTALLED_HEADERS)
 
 
+# Tests
+# Build the test programs against the freshly built libraries and run the
+# GPU-vs-CPU correctness tests for each supported integration order. The
+# backend selected above determines which test Makefile and binaries are used.
+ifeq ($(BACKEND), CUDA)
+    TEST_MAKEFILE := Makefile
+    TEST_SUFFIX := cuda
+else
+    TEST_MAKEFILE := Makefile_ocl
+    TEST_SUFFIX := ocl
+endif
+
+CORRECTNESS_TESTS := test_gravity_block_$(TEST_SUFFIX) \
+                     test_gravity_block_g5_$(TEST_SUFFIX) \
+                     test_gravity_block_6th_$(TEST_SUFFIX)
+
+.PHONY: build-tests
+build-tests: all
+	$(MAKE) -C tests -f $(TEST_MAKEFILE) CXX="$(CXX)" CC="$(CC)" \
+	    $(if $(CUDA_TK),CUDA_TK="$(CUDA_TK)")
+
+.PHONY: test
+test: build-tests
+	@for t in $(CORRECTNESS_TESTS); do \
+	    echo "=== Running $$t ==="; \
+	    ( cd tests && LD_LIBRARY_PATH="$(CURDIR):$$LD_LIBRARY_PATH" ./$$t ) || exit 1; \
+	done
+
+
 # Clean-up
 .PHONY: clean
 clean:
 	rm -f *.a *.so src/*.o src/SSE_AVX/SSE/*.o src/SSE_AVX/AVX/*.o
 	rm -f src/CUDA/*.ptx src/CUDA/*.ptxh src/OpenCL/*.cle src/OpenCL/*.clh
+	$(MAKE) -C tests -f Makefile clean
+	$(MAKE) -C tests -f Makefile_ocl clean
 
diff --git a/src/ocldev.h b/src/ocldev.h
index 68ea286..4a5b552 100644
--- a/src/ocldev.h
+++ b/src/ocldev.h
@@ -257,14 +257,29 @@ namespace dev {
         oclSafeCall(clGetPlatformInfo(PlatformIDs[dev], CL_PLATFORM_NAME, sizeof(platform_string), &platform_string, NULL));
 	std::cerr << " " << dev << ": " << platform_string << "\n";
       }
-      fprintf(stderr, "Using platform %d \n", platform_id);
-      PlatformID = PlatformIDs[platform_id];
+      
+      // Prefer NVIDIA platform if available.
+      int selected_platform = platform_id;
+      if (platform_id == 0 && numPlatforms > 1) {
+        for (cl_uint p = 0; p < numPlatforms; p++) {
+          char platform_string[1024];
+          oclSafeCall(clGetPlatformInfo(PlatformIDs[p], CL_PLATFORM_NAME, sizeof(platform_string), &platform_string, NULL));
+          if (strstr(platform_string, "NVIDIA") != NULL) {
+            std::cerr << "Found NVIDIA platform at index " << p << ", preferring it over others.\n";
+            selected_platform = p;
+            break;
+          }
+        }
+      }
+      
+      fprintf(stderr, "Using platform %d \n", selected_platform);
+      PlatformID = PlatformIDs[selected_platform];
 
       oclSafeCall(clGetDeviceIDs(PlatformID, DeviceType, 0, NULL, &DeviceCount));
 
       Devices.resize(DeviceCount);
       oclSafeCall(clGetDeviceIDs(PlatformID, DeviceType, DeviceCount, &Devices[0], &DeviceCount));
-
+    
       std::cerr << "Found " << DeviceCount << " suitable devices: \n";
       for (cl_uint dev = 0; dev < DeviceCount; dev++) {
 	char device_string[1024];
diff --git a/tests/Makefile_ocl b/tests/Makefile_ocl
index 11ea0c1..5d5c106 100644
--- a/tests/Makefile_ocl
+++ b/tests/Makefile_ocl
@@ -3,7 +3,7 @@ CXX ?= g++
 .SUFFIXES: .o .cpp .ptx .cu
 
 SAPPOROPATH=..
-SAPLIB2 = sapporo
+SAPLIB2 = sapporo2
 SAPLIB = lib$(SAPLIB2).a
 SAPLIBG6 = sapporoG6
 
@@ -28,7 +28,7 @@ PROG = test_gravity_block_ocl test_gravity_block_6th_ocl test_performance_rangeN
 all: $(OBJ) $(PROG) kernels
 
 kernels:
-	rm -f OpenCL && ln -s $(SAPPOROPATH)/OpenCL OpenCL
+	rm -f OpenCL && ln -s $(SAPPOROPATH)/src/OpenCL OpenCL
 
 test_gravity_block_ocl : test_gravity_block_ocl.o
 	$(CXX) $(LDFLAGS) $^ -o $@ -L $(SAPPOROPATH) -l$(SAPLIB2) $(LDFLAGS)