diff --git a/src/runtime/c/Makefile.am b/src/runtime/c/Makefile.am
index d46287d3b..c86f849b2 100644
--- a/src/runtime/c/Makefile.am
+++ b/src/runtime/c/Makefile.am
@@ -28,8 +28,7 @@ libpgf_la_SOURCES = \
 	pgf/namespace.h
 
 libpgf_la_LDFLAGS = -no-undefined
-# libpgf_la_LIBADD = -lrt
-libpgf_la_CXXFLAGS = -fno-rtti -std=c++11
+libpgf_la_CXXFLAGS = -fno-rtti -std=c++11 -DCOMPILING_PGF
 
 bin_PROGRAMS =