diff --git a/README.md b/README.md
index cfaaa34..7cc172b 100644
--- a/README.md
+++ b/README.md
@@ -110,8 +110,9 @@ BELOW HERE BE DRAGONS
 %%              By default, the following variables are defined:
 %%              CC       - C compiler
 %%              CXX      - C++ compiler
-%%              CFLAGS   - C compiler
-%%              CXXFLAGS - C++ compiler
+%%              CPPFLAGS   - C/C++ compiler preprocessor flags
+%%              CFLAGS   - C compiler flags
+%%              CXXFLAGS - C++ compiler flags
 %%              LDFLAGS  - Link flags
 %%              ERL_CFLAGS  - default -I paths for erts and ei
 %%              ERL_LDFLAGS - default -L and -lerl_interface -lei
diff --git a/src/pc_port_env.erl b/src/pc_port_env.erl
index 91d716b..bff108a 100644
--- a/src/pc_port_env.erl
+++ b/src/pc_port_env.erl
@@ -220,21 +220,21 @@ default_env() ->
      {"OBJDUMP", get_tool(Arch, "objdump", "objdump")},
 
      {"DRV_CXX_TEMPLATE",
-      "$CXX -c $CXXFLAGS $DRV_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
+      "$CXX -c $CPPFLAGS $CXXFLAGS $DRV_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
      {"DRV_CC_TEMPLATE",
-      "$CC -c $CFLAGS $DRV_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
+      "$CC -c $CPPFLAGS $CFLAGS $DRV_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
      {"DRV_LINK_TEMPLATE",
-      "$CC $PORT_IN_FILES $LDFLAGS $LDLIBS $DRV_LDFLAGS -o $PORT_OUT_FILE"},
+      "$CC $PORT_IN_FILES $CFLAGS $LDFLAGS $LDLIBS $DRV_LDFLAGS -o $PORT_OUT_FILE"},
      {"DRV_LINK_CXX_TEMPLATE",
-      "$CXX $PORT_IN_FILES $LDFLAGS $LDLIBS $DRV_LDFLAGS -o $PORT_OUT_FILE"},
+      "$CXX $PORT_IN_FILES $CXXFLAGS $LDFLAGS $LDLIBS $DRV_LDFLAGS -o $PORT_OUT_FILE"},
      {"EXE_CXX_TEMPLATE",
-      "$CXX -c $CXXFLAGS $EXE_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
+      "$CXX -c $CPPFLAGS $CXXFLAGS $EXE_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
      {"EXE_CC_TEMPLATE",
-      "$CC -c $CFLAGS $EXE_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
+      "$CC -c $CPPFLAGS $CFLAGS $EXE_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
      {"EXE_LINK_TEMPLATE",
-      "$CC $PORT_IN_FILES $LDFLAGS $EXE_LDFLAGS -o $PORT_OUT_FILE"},
+      "$CC $PORT_IN_FILES $CFLAGS $LDFLAGS $EXE_LDFLAGS -o $PORT_OUT_FILE"},
      {"EXE_LINK_CXX_TEMPLATE",
-      "$CXX $PORT_IN_FILES $LDFLAGS $EXE_LDFLAGS -o $PORT_OUT_FILE"},
+      "$CXX $PORT_IN_FILES $CXXFLAGS $LDFLAGS $EXE_LDFLAGS -o $PORT_OUT_FILE"},
      {"DRV_CFLAGS" , "-g -Wall -fPIC -MMD $ERL_CFLAGS"},
      {"DRV_LDFLAGS", "-shared $ERL_LDFLAGS"},
      {"EXE_CFLAGS" , "-g -Wall -fPIC -MMD $ERL_CFLAGS"},
@@ -282,18 +282,18 @@ default_env() ->
      {"win32", "LINKER", "link.exe"},
      {"win32", "DRV_CXX_TEMPLATE",
       %% DRV_* and EXE_* Templates are identical
-      "$CXX /c $CXXFLAGS $DRV_CFLAGS $PORT_IN_FILES /Fo$PORT_OUT_FILE"},
+      "$CXX /c $CPPFLAGS $CXXFLAGS $DRV_CFLAGS $PORT_IN_FILES /Fo$PORT_OUT_FILE"},
      {"win32", "DRV_CC_TEMPLATE",
-      "$CC /c $CFLAGS $DRV_CFLAGS $PORT_IN_FILES /Fo$PORT_OUT_FILE"},
+      "$CC /c $CPPFLAGS $CFLAGS $DRV_CFLAGS $PORT_IN_FILES /Fo$PORT_OUT_FILE"},
      {"win32", "DRV_LINK_TEMPLATE",
       "$LINKER $PORT_IN_FILES $LDFLAGS $DRV_LDFLAGS /OUT:$PORT_OUT_FILE"},
      {"win32", "DRV_LINK_CXX_TEMPLATE",
       "$LINKER $PORT_IN_FILES $LDFLAGS $DRV_LDFLAGS /OUT:$PORT_OUT_FILE"},
      %% DRV_* and EXE_* Templates are identical
      {"win32", "EXE_CXX_TEMPLATE",
-      "$CXX /c $CXXFLAGS $EXE_CFLAGS $PORT_IN_FILES /Fo$PORT_OUT_FILE"},
+      "$CXX /c $CPPFLAGS $CXXFLAGS $EXE_CFLAGS $PORT_IN_FILES /Fo$PORT_OUT_FILE"},
      {"win32", "EXE_CC_TEMPLATE",
-      "$CC /c $CFLAGS $EXE_CFLAGS $PORT_IN_FILES /Fo$PORT_OUT_FILE"},
+      "$CC /c $CPPFLAGS $CFLAGS $EXE_CFLAGS $PORT_IN_FILES /Fo$PORT_OUT_FILE"},
      {"win32", "EXE_LINK_TEMPLATE",
       "$LINKER $PORT_IN_FILES $LDFLAGS $EXE_LDFLAGS /OUT:$PORT_OUT_FILE"},
      {"win32", "EXE_LINK_CXX_TEMPLATE",