Index: uspace/Makefile.common
===================================================================
--- uspace/Makefile.common	(revision f5c80460a9886faf736b47c8926a4dae299030cc)
+++ uspace/Makefile.common	(revision e686889ccfd9de736c9b43f5bba55aa065b36861)
@@ -154,21 +154,26 @@
 JOBFILE = $(LIBC_PREFIX)/../../../tools/jobfile.py
 
+ifeq ($(POSIX_COMPAT),1)
+	CFLAGS = -I$(LIBCOMPAT_PREFIX)
+	LIBS += $(LIBCOMPAT_PREFIX)/libcompat.a
+endif
+
 ifeq ($(COMPILER),gcc_cross)
-	CFLAGS = $(GCC_CFLAGS) $(EXTRA_CFLAGS)
+	CFLAGS += $(GCC_CFLAGS) $(EXTRA_CFLAGS)
 	DEPEND_DEFS = $(DEFS) $(CONFIG_DEFS)
 endif
 
 ifeq ($(COMPILER),gcc_native)
-	CFLAGS = $(GCC_CFLAGS) $(EXTRA_CFLAGS)
+	CFLAGS += $(GCC_CFLAGS) $(EXTRA_CFLAGS)
 	DEPEND_DEFS = $(DEFS) $(CONFIG_DEFS)
 endif
 
 ifeq ($(COMPILER),icc)
-	CFLAGS = $(ICC_CFLAGS) $(EXTRA_CFLAGS)
+	CFLAGS += $(ICC_CFLAGS) $(EXTRA_CFLAGS)
 	DEPEND_DEFS = $(DEFS) $(CONFIG_DEFS)
 endif
 
 ifeq ($(COMPILER),clang)
-	CFLAGS = $(CLANG_CFLAGS) $(EXTRA_CFLAGS)
+	CFLAGS += $(CLANG_CFLAGS) $(EXTRA_CFLAGS)
 	DEPEND_DEFS = $(DEFS) $(CONFIG_DEFS)
 endif