diff --git a/cmd/gogensig/convert/_testdata/forwarddecl/conf/llcppg.cfg b/cmd/gogensig/convert/_testdata/forwarddecl/conf/llcppg.cfg
index 1bc8f49..92eadf2 100644
--- a/cmd/gogensig/convert/_testdata/forwarddecl/conf/llcppg.cfg
+++ b/cmd/gogensig/convert/_testdata/forwarddecl/conf/llcppg.cfg
@@ -1,6 +1,6 @@
 {
   "name": "forwarddecl",
-  "include": ["temp.h"],
+  "include": ["temp.h", "impl.h"],
   "trimPrefixes": ["sqlite3_","lua_"],
   "cplusplus":false
 }
diff --git a/cmd/gogensig/convert/_testdata/forwarddecl/gogensig.expect b/cmd/gogensig/convert/_testdata/forwarddecl/gogensig.expect
index 41a7066..900fe37 100644
--- a/cmd/gogensig/convert/_testdata/forwarddecl/gogensig.expect
+++ b/cmd/gogensig/convert/_testdata/forwarddecl/gogensig.expect
@@ -10,6 +10,10 @@ type Foo struct {
 	A c.Long
 }
 
+type File struct {
+	Unused [8]uint8
+}
+
 ===== temp.go =====
 package forwarddecl
 
@@ -22,10 +26,6 @@ type Bar struct {
 	A *Foo
 }
 
-type File struct {
-	PMethods *IoMethods
-}
-
 type IoMethods struct {
 	XUnfetch unsafe.Pointer
 }
@@ -112,6 +112,7 @@ Fts5Context
 Fts5ExtensionApi
 Fts5PhraseIter
 bar Bar
+foo Foo
 fts5_extension_function Fts5ExtensionFunction
 lua_Debug Debug
 lua_State State
diff --git a/cmd/gogensig/convert/_testdata/forwarddecl/hfile/impl.h b/cmd/gogensig/convert/_testdata/forwarddecl/hfile/impl.h
index 9bf447b..c2d3d88 100644
--- a/cmd/gogensig/convert/_testdata/forwarddecl/hfile/impl.h
+++ b/cmd/gogensig/convert/_testdata/forwarddecl/hfile/impl.h
@@ -1,4 +1,7 @@
-struct foo
-{
+struct foo {
     long a;
 };
+
+// Forward declaration of sqlite3_file
+// todo: the sqlite3_file 's real type should be defined.
+struct sqlite3_file;
diff --git a/cmd/gogensig/convert/_testdata/forwarddecl/hfile/temp.h b/cmd/gogensig/convert/_testdata/forwarddecl/hfile/temp.h
index 1bb32ae..26ee1e7 100644
--- a/cmd/gogensig/convert/_testdata/forwarddecl/hfile/temp.h
+++ b/cmd/gogensig/convert/_testdata/forwarddecl/hfile/temp.h
@@ -1,25 +1,21 @@
 #include "impl.h"
 typedef struct foo foo;
-struct bar
-{
+struct bar {
     foo *a;
 };
 
 typedef struct sqlite3_file sqlite3_file;
-struct sqlite3_file
-{
+struct sqlite3_file {
     const struct sqlite3_io_methods *pMethods; /* Methods for an open file */
 };
 
 typedef struct sqlite3_io_methods sqlite3_io_methods;
-struct sqlite3_io_methods
-{
+struct sqlite3_io_methods {
     int (*xUnfetch)(sqlite3_file *, int iOfst, void *p);
 };
 
 typedef struct sqlite3_pcache_page sqlite3_pcache_page;
-struct sqlite3_pcache_page
-{
+struct sqlite3_pcache_page {
     void *pBuf;
     void *pExtra;
 };
@@ -27,8 +23,7 @@ struct sqlite3_pcache_page
 typedef struct sqlite3_pcache sqlite3_pcache;
 
 typedef struct sqlite3_pcache_methods2 sqlite3_pcache_methods2;
-struct sqlite3_pcache_methods2
-{
+struct sqlite3_pcache_methods2 {
     int iVersion;
     void *pArg;
     int (*xInit)(void *);
@@ -52,8 +47,7 @@ typedef struct lua_Debug lua_Debug;
 
 int(lua_getstack)(lua_State *L, int level, lua_Debug *ar);
 
-struct lua_Debug
-{
+struct lua_Debug {
     int event;
     const char *name;
     const char *namewhat;
@@ -86,8 +80,7 @@ typedef void (*fts5_extension_function)(const Fts5ExtensionApi *pApi, /* API off
                                         sqlite3_value **apVal         /* Array of trailing arguments */
 );
 
-struct Fts5PhraseIter
-{
+struct Fts5PhraseIter {
     const unsigned char *a;
     const unsigned char *b;
 };
\ No newline at end of file
diff --git a/cmd/gogensig/convert/package.go b/cmd/gogensig/convert/package.go
index c467195..bcaef32 100644
--- a/cmd/gogensig/convert/package.go
+++ b/cmd/gogensig/convert/package.go
@@ -236,8 +236,12 @@ func (p *Package) NewTypeDecl(typeDecl *ast.TypeDecl) error {
 	}
 
 	cname := typeDecl.Name.Name
+	isForward := p.cvt.inComplete(typeDecl.Type)
 	name, changed, err := p.DeclName(cname)
 	if err != nil {
+		if isForward {
+			return nil
+		}
 		return err
 	}
 	p.CollectNameMapping(cname, name)
@@ -248,7 +252,7 @@ func (p *Package) NewTypeDecl(typeDecl *ast.TypeDecl) error {
 		substObj(p.p.Types, p.p.Types.Scope(), cname, decl.Type().Obj())
 	}
 
-	if !p.cvt.inComplete(typeDecl.Type) {
+	if !isForward {
 		if err := p.handleCompleteType(decl, typeDecl.Type, cname); err != nil {
 			return err
 		}
diff --git a/cmd/gogensig/convert/package_test.go b/cmd/gogensig/convert/package_test.go
index 72dace4..95629bd 100644
--- a/cmd/gogensig/convert/package_test.go
+++ b/cmd/gogensig/convert/package_test.go
@@ -1588,17 +1588,17 @@ func TestForwardDecl(t *testing.T) {
 		),
 	})
 
-	// forward decl
-	err := pkg.NewTypeDecl(&ast.TypeDecl{
+	forwardDecl := &ast.TypeDecl{
 		Name: &ast.Ident{Name: "Foo"},
 		Type: &ast.RecordType{
 			Tag:    ast.Struct,
 			Fields: &ast.FieldList{},
 		},
-	})
-
+	}
+	// forward decl
+	err := pkg.NewTypeDecl(forwardDecl)
 	if err != nil {
-		t.Fatalf("NewTypeDecl failed: %v", err)
+		t.Fatalf("Forward decl failed: %v", err)
 	}
 
 	// complete decl
@@ -1621,6 +1621,12 @@ func TestForwardDecl(t *testing.T) {
 		t.Fatalf("NewTypeDecl failed: %v", err)
 	}
 
+	err = pkg.NewTypeDecl(forwardDecl)
+
+	if err != nil {
+		t.Fatalf("NewTypeDecl failed: %v", err)
+	}
+
 	expect := `
 package testpkg