diff --git a/project/common.mk b/project/common.mk
index 32cbf84..a46a3b0 100644
--- a/project/common.mk
+++ b/project/common.mk
@@ -1,8 +1,7 @@
-COMMON_SRCS = \
+API_SRCS = \
 	src/driver/sfrt_amain.c \
 	src/driver/sfrt_driver_ctx.c \
 	src/driver/sfrt_unit_ctx.c \
-	src/internal/sofort_errinfo_impl.c \
 	src/logic/sfrt_map_input.c \
 	src/output/sfrt_output_address.c \
 	src/output/sfrt_output_dummy.c \
@@ -10,5 +9,10 @@ COMMON_SRCS = \
 	src/output/sfrt_output_name.c \
 	src/skin/sfrt_skin_default.c \
 
+INTERNAL_SRCS = \
+	src/internal/$(PACKAGE)_errinfo_impl.c \
+
 APP_SRCS = \
 	src/sofort.c
+
+COMMON_SRCS = $(API_SRCS) $(INTERNAL_SRCS)