diff --git a/com.oracle.truffle.r.native/fficall/jni/Makefile b/com.oracle.truffle.r.native/fficall/jni/Makefile
index 3f14954c3d05028a97f150177b016fb825426240..a01d09c277036db4dd6e20d911d989407c70d925 100644
--- a/com.oracle.truffle.r.native/fficall/jni/Makefile
+++ b/com.oracle.truffle.r.native/fficall/jni/Makefile
@@ -38,8 +38,13 @@ C_LIBNAME := librfficall$(DYLIB_EXT)
 C_OBJECTS := $(subst $(SRC),$(OBJ),$(C_SOURCES:.c=.o))
 C_LIB := $(TOPDIR)/builtinlibs/$(OBJ)/$(C_LIBNAME)
 CFLAGS := $(CFLAGS) -DFASTR
+ifeq ($(OS_DIR),sunos)
+OS_INCLUDE := solaris
+else
+OS_INCLUDE := $(OS_DIR)
+endif
 
-JNI_INCLUDES = -I $(JAVA_HOME)/include -I $(JAVA_HOME)/include/$(OS_DIR)
+JNI_INCLUDES = -I $(JAVA_HOME)/include -I $(JAVA_HOME)/include/$(OS_INCLUDE)
 FFI_INCLUDES = -I$(TOPDIR)/include/jni/include -I$(TOPDIR)/include/jni/include/R_ext
 
 INCLUDES := $(JNI_INCLUDES) $(FFI_INCLUDES)