diff --git a/build/ck.build.in b/build/ck.build.in
index 6bcd044..1d6bfe3 100644
--- a/build/ck.build.in
+++ b/build/ck.build.in
@@ -2,8 +2,8 @@ CC=@CC@
 MAKE=make
 SRC_DIR=@SRC_DIR@
 BUILD_DIR=@BUILD_DIR@
-CFLAGS=@CFLAGS@ -I$(SRC_DIR)/include -I$(BUILD_DIR)/include
-LDFLAGS=@LDFLAGS@
+CFLAGS+=@CFLAGS@ -I$(SRC_DIR)/include -I$(BUILD_DIR)/include
+LDFLAGS+=@LDFLAGS@
 ALL_LIBS=@ALL_LIBS@
 LD=@LD@