diff --git a/src/test/Makefile b/src/test/Makefile
index 56b1965178..d89c1aa725 100644
--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -11,6 +11,7 @@
 
 # Where to find user code.
 USER_DIR = ../main
+TEST_DIR = unit
 
 
 # specify which files that are included in the test in addition to the unittest file.
@@ -35,7 +36,7 @@ arming_prevention_unittest_SRC := \
 		$(USER_DIR)/fc/runtime_config.c \
 		$(USER_DIR)/common/bitarray.c
 
-atomic_unittest_SRC = \
+atomic_unittest_SRC := \
 		$(USER_DIR)/build/atomic.c \
 		$(TEST_DIR)/atomic_unittest_c.c
 
@@ -291,7 +292,6 @@ ringbuffer_unittest_SRC := \
 GTEST_DIR = ../../lib/test/gtest
 
 
-TEST_DIR = unit
 USER_INCLUDE_DIR = $(USER_DIR)
 
 OBJECT_DIR = ../../obj/test
@@ -313,10 +313,14 @@ COMMON_FLAGS = \
 	-ggdb3 \
 	-O0 \
 	-DUNIT_TEST \
-	-fblocks \
 	-isystem $(GTEST_DIR)/inc \
 	-MMD -MP
 
+ifeq ($(shell $(CC) -v 2>&1 | grep -q "clang version" && echo "clang"),clang)
+COMMON_FLAGS += -fblocks
+LDFLAGS	     += -lBlocksRuntime
+endif
+
 ifneq ($(UNAME), Darwin)
 COMMON_FLAGS += -pthread
 endif
@@ -337,9 +341,9 @@ CXX_FLAGS += $(COVERAGE_FLAGS)
 
 # Set up the parameter group linker flags according to OS
 ifeq ($(UNAME), Darwin)
-PG_FLAGS = -Wl,-map,$(OBJECT_DIR)/$@.map
+LDFLAGS  += -Wl,-map,$(OBJECT_DIR)/$@.map
 else
-PG_FLAGS = -Wl,-T,$(TEST_DIR)/parameter_group.ld -Wl,-Map,$(OBJECT_DIR)/$@.map
+LDFLAGS  += -Wl,-T,$(TEST_DIR)/parameter_group.ld -Wl,-Map,$(OBJECT_DIR)/$@.map
 endif
 
 # Gather up all of the tests.
@@ -479,7 +483,7 @@ $(OBJECT_DIR)/$1/$1 : $$($$1_OBJS) \
 
 	@echo "linking $$@" "$(STDOUT)"
 	$(V1) mkdir -p $(dir $$@)
-	$(V1) $(CXX) $(CXX_FLAGS) $(PG_FLAGS) -lBlocksRuntime $$^ -o $$@
+	$(V1) $(CXX) $(CXX_FLAGS) $(LDFLAGS) $$^ -o $$@
 
 test_$1: $(OBJECT_DIR)/$1/$1
 	$(V1) $$< $$(EXEC_OPTS) "$(STDOUT)" && echo "running $$@: PASS"
diff --git a/src/test/unit/atomic_unittest.cc b/src/test/unit/atomic_unittest.cc
index 17f9275bc8..39c4bf23a8 100644
--- a/src/test/unit/atomic_unittest.cc
+++ b/src/test/unit/atomic_unittest.cc
@@ -61,8 +61,6 @@ TEST(AtomicUnittest, TestAtomicBlockNB)
     EXPECT_EQ(atomic_BASEPRI, 0);          // restore priority to unlocked
 }
 
-#if 1  // not working now ... (CLang needs -fblock + libraries / some unittests don't support gcc)
-
 struct barrierTrace {
     int enter, leave;
 };
@@ -112,5 +110,3 @@ TEST(AtomicUnittest, TestAtomicBarrier)
     //return sIdx;
     EXPECT_EQ(sIdx, sampled);
 }
-
-#endif