diff --git a/androidbp/cmd/androidbp.go b/androidbp/cmd/androidbp.go
index a5cf91a..ef7a364 100644
--- a/androidbp/cmd/androidbp.go
+++ b/androidbp/cmd/androidbp.go
@@ -218,6 +218,19 @@
 	return
 }
 
+func appendAssign(name string, prop *bpparser.Property, suffix *string) ([]string, error) {
+	if suffix != nil {
+		name += "_" + *suffix
+	}
+	val, err := valueToString(prop.Value)
+	if err != nil {
+		return nil, err
+	}
+	return []string{
+		fmt.Sprintf("%s += %s", name, val),
+	}, nil
+}
+
 func prependLocalPath(name string, prop *bpparser.Property, suffix *string) ([]string, error) {
 	if suffix != nil {
 		name += "_" + *suffix
@@ -227,7 +240,7 @@
 		return nil, err
 	}
 	return []string{
-		fmt.Sprintf("%s := $(addprefix $(LOCAL_PATH)/,%s)\n", name, val),
+		fmt.Sprintf("%s += $(addprefix $(LOCAL_PATH)/,%s)", name, val),
 	}, nil
 }
 
diff --git a/androidbp/cmd/soong.go b/androidbp/cmd/soong.go
index ff026a4..ecae5b0 100644
--- a/androidbp/cmd/soong.go
+++ b/androidbp/cmd/soong.go
@@ -27,7 +27,6 @@
 	"static_libs":        {"LOCAL_STATIC_LIBRARIES", bpparser.List},
 	"whole_static_libs":  {"LOCAL_WHOLE_STATIC_LIBRARIES", bpparser.List},
 	"system_shared_libs": {"LOCAL_SYSTEM_SHARED_LIBRARIES", bpparser.List},
-	"include_dirs":       {"LOCAL_C_INCLUDES", bpparser.List},
 	"asflags":            {"LOCAL_ASFLAGS", bpparser.List},
 	"clang_asflags":      {"LOCAL_CLANG_ASFLAGS", bpparser.List},
 	"cflags":             {"LOCAL_CFLAGS", bpparser.List},
@@ -66,6 +65,7 @@
 	string
 	f func(name string, prop *bpparser.Property, suffix *string) ([]string, error)
 }{
+	"include_dirs":        {"LOCAL_C_INCLUDES", appendAssign},
 	"local_include_dirs":  {"LOCAL_C_INCLUDES", prependLocalPath},
 	"export_include_dirs": {"LOCAL_EXPORT_C_INCLUDE_DIRS", prependLocalPath},
 	"suffix":              {"LOCAL_MODULE_STEM", prependLocalModule},