diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index 30908c369..0e7f300cf 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -119,8 +119,8 @@ PgfDB *pgf_read_ngf(const char *fpath,
                 is_new = true;
                 pgf = PgfDB::malloc<PgfPGF>(master.size+1);
                 pgf->ref_count = 1;
-                pgf->major_version = 2;
-                pgf->minor_version = 0;
+                pgf->major_version = PGF_MAJOR_VERSION;
+                pgf->minor_version = PGF_MINOR_VERSION;
                 pgf->gflags = 0;
                 pgf->abstract.name = PgfDB::malloc<PgfText>();
                 pgf->abstract.name->size = 0;
diff --git a/src/runtime/c/pgf/pgf.h b/src/runtime/c/pgf/pgf.h
index fbb26d187..2710b3c03 100644
--- a/src/runtime/c/pgf/pgf.h
+++ b/src/runtime/c/pgf/pgf.h
@@ -40,6 +40,9 @@
 #include<stdint.h>
 #include <sys/types.h>
 
+#define PGF_MAJOR_VERSION 2
+#define PGF_MINOR_VERSION 1
+
 /* A generic structure to store text. The last field is variable length */
 typedef struct {
     size_t size;
diff --git a/src/runtime/c/pgf/reader.cxx b/src/runtime/c/pgf/reader.cxx
index f69cf9cd7..4d57ac280 100644
--- a/src/runtime/c/pgf/reader.cxx
+++ b/src/runtime/c/pgf/reader.cxx
@@ -437,6 +437,11 @@ ref<PgfPGF> PgfReader::read_pgf()
     pgf->major_version = read_u16be();
     pgf->minor_version = read_u16be();
 
+    if (pgf->major_version != PGF_MAJOR_VERSION ||
+        pgf->minor_version != PGF_MINOR_VERSION) {
+        throw pgf_error("Unsupported format version");
+    }
+
     pgf->gflags = read_namespace<PgfFlag>(&PgfReader::read_flag);
 
     read_abstract(ref<PgfAbstr>::from_ptr(&pgf->abstract));