diff --git a/src/adb.c b/src/adb.c
index 4f313cd..144efff 100644
--- a/src/adb.c
+++ b/src/adb.c
@@ -764,7 +764,7 @@ adb_val_t adb_w_fromstring(struct adb *db, const uint8_t *kind, apk_blob_t val)
 		adb_wo_alloca(&obj, schema, db);
 		if (!schema->fromstring) return ADB_ERROR(APKE_ADB_NO_FROMSTRING);
 		r = schema->fromstring(&obj, val);
-		if (r) return ADB_ERROR(r);
+		if (r) return ADB_ERROR(-r);
 		return adb_w_obj(&obj);
 		}
 	default:
@@ -849,7 +849,7 @@ adb_val_t adb_w_arr(struct adb_obj *o)
 	return __adb_w_obj(o, ADB_TYPE_ARRAY);
 }
 
-adb_val_t adb_wo_fromstring(struct adb_obj *o, apk_blob_t val)
+int adb_wo_fromstring(struct adb_obj *o, apk_blob_t val)
 {
 	adb_wo_reset(o);
 	return o->schema->fromstring(o, val);
diff --git a/src/adb.h b/src/adb.h
index a306d05..c46f7cc 100644
--- a/src/adb.h
+++ b/src/adb.h
@@ -213,7 +213,7 @@ void adb_wo_reset(struct adb_obj *);
 void adb_wo_resetdb(struct adb_obj *);
 adb_val_t adb_w_obj(struct adb_obj *);
 adb_val_t adb_w_arr(struct adb_obj *);
-adb_val_t adb_wo_fromstring(struct adb_obj *o, apk_blob_t);
+int adb_wo_fromstring(struct adb_obj *o, apk_blob_t);
 adb_val_t adb_wo_val(struct adb_obj *o, unsigned i, adb_val_t);
 adb_val_t adb_wo_val_fromstring(struct adb_obj *o, unsigned i, apk_blob_t);
 adb_val_t adb_wo_int(struct adb_obj *o, unsigned i, uint32_t);
diff --git a/src/apk_adb.c b/src/apk_adb.c
index c7fbdde..37206f0 100644
--- a/src/apk_adb.c
+++ b/src/apk_adb.c
@@ -116,6 +116,12 @@ const struct adb_object_schema schema_string_array = {
 	.fields = ADB_ARRAY_ITEM(scalar_string),
 };
 
+static adb_val_t version_fromstring(struct adb *db, apk_blob_t val)
+{
+	if (!apk_version_validate(val)) return ADB_ERROR(APKE_PKGVERSION_FORMAT);
+	return adb_w_blob(db, val);
+}
+
 static int version_compare(struct adb *db1, adb_val_t v1, struct adb *db2, adb_val_t v2)
 {
 	switch (apk_version_compare_blob(adb_r_blob(db1, v1), adb_r_blob(db2, v2))) {
@@ -128,7 +134,7 @@ static int version_compare(struct adb *db1, adb_val_t v1, struct adb *db2, adb_v
 static struct adb_scalar_schema scalar_version = {
 	.kind = ADB_KIND_BLOB,
 	.tostring = string_tostring,
-	.fromstring = string_fromstring,
+	.fromstring = version_fromstring,
 	.compare = version_compare,
 };
 
@@ -327,7 +333,7 @@ static int dependency_fromstring(struct adb_obj *obj, apk_blob_t bdep)
 	return 0;
 
 fail:
-	return -APKE_ADB_DEPENDENCY_FORMAT;
+	return -APKE_DEPENDENCY_FORMAT;
 }
 
 static int dependency_cmp(const struct adb_obj *o1, const struct adb_obj *o2)
@@ -356,7 +362,8 @@ static int dependencies_fromstring(struct adb_obj *obj, apk_blob_t b)
 	adb_wo_alloca(&dep, &schema_dependency, obj->db);
 
 	while (apk_dep_split(&b, &bdep)) {
-		adb_wo_fromstring(&dep, bdep);
+		int r = adb_wo_fromstring(&dep, bdep);
+		if (r) return r;
 		adb_wa_append_obj(obj, &dep);
 	}
 
diff --git a/src/apk_defines.h b/src/apk_defines.h
index 27f31ef..9cacf13 100644
--- a/src/apk_defines.h
+++ b/src/apk_defines.h
@@ -44,6 +44,8 @@ enum {
 	APKE_SIGNATURE_UNTRUSTED,
 	APKE_SIGNATURE_INVALID,
 	APKE_FORMAT_NOT_SUPPORTED,
+	APKE_PKGVERSION_FORMAT,
+	APKE_DEPENDENCY_FORMAT,
 	APKE_ADB_COMPRESSION,
 	APKE_ADB_HEADER,
 	APKE_ADB_VERSION,
@@ -52,7 +54,6 @@ enum {
 	APKE_ADB_SIGNATURE,
 	APKE_ADB_NO_FROMSTRING,
 	APKE_ADB_LIMIT,
-	APKE_ADB_DEPENDENCY_FORMAT,
 	APKE_ADB_PACKAGE_FORMAT,
 	APKE_V2DB_FORMAT,
 	APKE_V2PKG_FORMAT,
diff --git a/src/app_mkpkg.c b/src/app_mkpkg.c
index 4e61066..afbc150 100644
--- a/src/app_mkpkg.c
+++ b/src/app_mkpkg.c
@@ -242,8 +242,8 @@ static int mkpkg_main(void *pctx, struct apk_ctx *ac, struct apk_string_array *a
 
 	// prepare package info
 	for (i = 0; i < ARRAY_SIZE(ctx->info); i++) {
-		apk_blob_t val = ctx->info[i];
-		if (APK_BLOB_IS_NULL(val)) {
+		apk_blob_t b = ctx->info[i];
+		if (APK_BLOB_IS_NULL(b)) {
 			switch (i) {
 			case ADBI_PI_NAME:
 			case ADBI_PI_VERSION:
@@ -254,7 +254,13 @@ static int mkpkg_main(void *pctx, struct apk_ctx *ac, struct apk_string_array *a
 			}
 			continue;
 		}
-		adb_wo_val_fromstring(&pkgi, i, val);
+		adb_val_t val = adb_wo_val_fromstring(&pkgi, i, b);
+		if (ADB_IS_ERROR(val)) {
+			r = ADB_VAL_VALUE(val);
+			apk_err(out, "field '%s' has invalid value: %s",
+				schema_pkginfo.fields[i-1].name, apk_error_str(r));
+			goto err;
+		}
 	}
 	if (adb_ro_val(&pkgi, ADBI_PI_ARCH) == ADB_VAL_NULL)
 		adb_wo_blob(&pkgi, ADBI_PI_ARCH, APK_BLOB_STRLIT(APK_DEFAULT_ARCH));
diff --git a/src/print.c b/src/print.c
index 187dcf4..4ffc536 100644
--- a/src/print.c
+++ b/src/print.c
@@ -39,6 +39,8 @@ const char *apk_error_str(int error)
 	case APKE_SIGNATURE_UNTRUSTED:		return "UNTRUSTED signature";
 	case APKE_SIGNATURE_INVALID:		return "BAD signature";
 	case APKE_FORMAT_NOT_SUPPORTED:		return "file format not supported (in this applet)";
+	case APKE_PKGVERSION_FORMAT:		return "package version is invalid";
+	case APKE_DEPENDENCY_FORMAT:		return "dependency format is invalid";
 	case APKE_ADB_COMPRESSION:		return "ADB compression not supported";
 	case APKE_ADB_HEADER:			return "ADB header error";
 	case APKE_ADB_VERSION:			return "incompatible ADB version";
@@ -47,7 +49,6 @@ const char *apk_error_str(int error)
 	case APKE_ADB_SIGNATURE:		return "ADB signature block error";
 	case APKE_ADB_NO_FROMSTRING:		return "ADB schema error (no fromstring)";
 	case APKE_ADB_LIMIT:			return "ADB schema limit reached";
-	case APKE_ADB_DEPENDENCY_FORMAT:	return "ADB dependency format";
 	case APKE_ADB_PACKAGE_FORMAT:		return "ADB package format";
 	case APKE_V2DB_FORMAT:			return "v2 database format error";
 	case APKE_V2PKG_FORMAT:			return "v2 package format error";