diff --git a/source/backend/Makefile.mk b/source/backend/Makefile.mk
index 8448f46c2..f92b76918 100644
--- a/source/backend/Makefile.mk
+++ b/source/backend/Makefile.mk
@@ -24,7 +24,7 @@ endif
 
 # ----------------------------------------------------------------------------------------------------------------------------
 
-BUILD_CXX_FLAGS += -I. -I.. -I$(CWD) -I$(CWD)/includes -I$(CWD)/utils -isystem $(CWD)/modules
+BUILD_CXX_FLAGS += -I. -I.. -I$(CWD) -I$(CWD)/includes -I$(CWD)/modules -I$(CWD)/utils
 BUILD_CXX_FLAGS += $(LIBLO_FLAGS)
 
 # ----------------------------------------------------------------------------------------------------------------------------
diff --git a/source/bridges-plugin/Makefile b/source/bridges-plugin/Makefile
index a91f6b867..7dbaea0ba 100644
--- a/source/bridges-plugin/Makefile
+++ b/source/bridges-plugin/Makefile
@@ -22,7 +22,7 @@ endif
 
 # ----------------------------------------------------------------------------------------------------------------------
 
-BUILD_CXX_FLAGS += -DBUILD_BRIDGE -I. -I$(CWD) -I$(CWD)/backend -I$(CWD)/includes -I$(CWD)/utils -isystem $(CWD)/modules
+BUILD_CXX_FLAGS += -DBUILD_BRIDGE -I. -I$(CWD) -I$(CWD)/backend -I$(CWD)/includes -I$(CWD)/modules -I$(CWD)/utils
 BUILD_CXX_FLAGS += -I$(CWD)/backend/engine -I$(CWD)/backend/plugin
 BUILD_CXX_FLAGS += $(LIBLO_FLAGS)
 
diff --git a/source/discovery/Makefile b/source/discovery/Makefile
index cded23d18..aa3a19a08 100644
--- a/source/discovery/Makefile
+++ b/source/discovery/Makefile
@@ -28,7 +28,7 @@ endif
 
 # ----------------------------------------------------------------------------------------------------------------------------
 
-BUILD_CXX_FLAGS += -I$(CWD)/backend -I$(CWD)/includes -I$(CWD)/utils -isystem $(CWD)/modules
+BUILD_CXX_FLAGS += -I$(CWD)/backend -I$(CWD)/includes -I$(CWD)/modules -I$(CWD)/utils
 
 ifeq ($(MACOS),true)
 BUILD_CXX_FLAGS += -ObjC++
diff --git a/source/plugin/Makefile b/source/plugin/Makefile
index bfe60b3f3..0466d95f8 100644
--- a/source/plugin/Makefile
+++ b/source/plugin/Makefile
@@ -21,7 +21,7 @@ endif
 
 # ----------------------------------------------------------------------------------------------------------------------------
 
-BUILD_CXX_FLAGS += -I$(CWD)/backend -I$(CWD)/includes -I$(CWD)/utils -isystem $(CWD)/modules
+BUILD_CXX_FLAGS += -I$(CWD)/backend -I$(CWD)/includes -I$(CWD)/modules -I$(CWD)/utils
 BUILD_CXX_FLAGS += $(NATIVE_PLUGINS_FLAGS)
 
 ifeq ($(HAVE_LIBLO),true)