diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index 1374d3667..1c90bbf3c 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -49,7 +49,7 @@ PgfDB *pgf_read_pgf(const char* fpath,
         {
             DB_scope scope(db, WRITER_SCOPE);
 
-            PgfReader rdr(in, fpath);
+            PgfReader rdr(in);
             ref<PgfPGF> pgf = rdr.read_pgf();
 
             PgfDB::set_revision(pgf);
@@ -88,7 +88,7 @@ PgfDB *pgf_boot_ngf(const char* pgf_path, const char* ngf_path,
         {
             DB_scope scope(db, WRITER_SCOPE);
 
-            PgfReader rdr(in, pgf_path);
+            PgfReader rdr(in);
             ref<PgfPGF> pgf = rdr.read_pgf();
 
             PgfDB::set_revision(pgf);
@@ -200,7 +200,7 @@ void pgf_write_pgf(const char* fpath,
             DB_scope scope(db, READER_SCOPE);
             ref<PgfPGF> pgf = PgfDB::revision2pgf(revision);
 
-            PgfWriter wtr(out, fpath);
+            PgfWriter wtr(out);
             wtr.write_pgf(pgf);
         }
     } PGF_API_END
diff --git a/src/runtime/c/pgf/reader.cxx b/src/runtime/c/pgf/reader.cxx
index 45ea438d7..cb0e7098a 100644
--- a/src/runtime/c/pgf/reader.cxx
+++ b/src/runtime/c/pgf/reader.cxx
@@ -3,10 +3,9 @@
 #include <math.h>
 #include <string.h>
 
-PgfReader::PgfReader(FILE *in, const char *filepath)
+PgfReader::PgfReader(FILE *in)
 {
     this->in = in;
-    this->filepath = filepath;
 }
 
 uint8_t PgfReader::read_uint8()
@@ -14,9 +13,9 @@ uint8_t PgfReader::read_uint8()
     uint8_t b;
     size_t n_bytes = fread((char*) &b, sizeof(b), 1, in);
     if (feof(in))
-        throw pgf_error("reached end of file while reading a grammar");
+        throw pgf_error("reached end of file while reading the grammar");
     if (ferror(in))
-        throw pgf_systemerror(ferror(in), filepath);
+        throw pgf_error("an error occured while reading the grammar");
 
 	return b;
 }
@@ -28,7 +27,7 @@ uint16_t PgfReader::read_u16be()
     if (feof(in))
         throw pgf_error("reached end of file while reading a grammar");
     if (ferror(in))
-        throw pgf_systemerror(ferror(in), filepath);
+        throw pgf_error("an error occured while reading the grammar");
 
 	return (((uint16_t) buf[0]) << 8 | buf[1]);
 }
@@ -40,7 +39,7 @@ uint64_t PgfReader::read_u64be()
     if (feof(in))
         throw pgf_error("reached end of file while reading a grammar");
     if (ferror(in))
-        throw pgf_systemerror(ferror(in), filepath);
+        throw pgf_error("an error occured while reading the grammar");
 
 	return (((uint64_t) buf[0]) << 56 |
             ((uint64_t) buf[1]) << 48 |
@@ -96,7 +95,7 @@ object PgfReader::read_name_internal(size_t struct_size)
     if (feof(in))
         throw pgf_error("utf8 decoding error");
     if (ferror(in))
-        throw pgf_systemerror(ferror(in), filepath);
+        throw pgf_error("an error occured while reading the grammar");
 
     ptext->text[size] = 0;
 
@@ -132,7 +131,7 @@ object PgfReader::read_text_internal(size_t struct_size)
         if (feof(in))
             throw pgf_error("utf8 decoding error");
         if (ferror(in))
-            throw pgf_systemerror(ferror(in), filepath);
+            throw pgf_error("an error occured while reading the grammar");
 
         p += len;
 	}
diff --git a/src/runtime/c/pgf/reader.h b/src/runtime/c/pgf/reader.h
index b14bc6665..3cb097d97 100644
--- a/src/runtime/c/pgf/reader.h
+++ b/src/runtime/c/pgf/reader.h
@@ -8,7 +8,7 @@
 class PGF_INTERNAL_DECL PgfReader
 {
 public:
-    PgfReader(FILE *in, const char *filepath);
+    PgfReader(FILE *in);
 
     uint8_t read_uint8();
     uint16_t read_u16be();
@@ -72,7 +72,6 @@ public:
 
 private:
     FILE *in;
-    const char* filepath;
 
     object read_name_internal(size_t struct_size);
     object read_text_internal(size_t struct_size);
diff --git a/src/runtime/c/pgf/writer.cxx b/src/runtime/c/pgf/writer.cxx
index 74728e61a..4a2278015 100644
--- a/src/runtime/c/pgf/writer.cxx
+++ b/src/runtime/c/pgf/writer.cxx
@@ -2,10 +2,9 @@
 #include "data.h"
 #include "writer.h"
 
-PgfWriter::PgfWriter(FILE *out, const char *filepath)
+PgfWriter::PgfWriter(FILE *out)
 {
     this->out = out;
-    this->filepath = filepath;
     this->abstract = 0;
 }
 
@@ -13,7 +12,7 @@ void PgfWriter::write_uint8(uint8_t b)
 {
     size_t n_items = fwrite(&b, sizeof(b), 1, out);
     if (ferror(out))
-        throw pgf_systemerror(ferror(out), filepath);
+        throw pgf_error("an error occured while writing out the grammar");
     if (n_items != 1)
         throw pgf_error("couldn't write to the output file");
 }
@@ -26,7 +25,7 @@ void PgfWriter::write_u16be(uint16_t u)
 
     size_t n_items = fwrite(&buf, sizeof(buf), 1, out);
     if (ferror(out))
-        throw pgf_systemerror(ferror(out), filepath);
+        throw pgf_error("an error occured while writing out the grammar");
     if (n_items != 1)
         throw pgf_error("couldn't write to the output file");
 }
@@ -45,7 +44,7 @@ void PgfWriter::write_u64be(uint64_t u)
 
     size_t n_items = fwrite(&buf, sizeof(buf), 1, out);
     if (ferror(out))
-        throw pgf_systemerror(ferror(out), filepath);
+        throw pgf_error("an error occured while writing out the grammar");
     if (n_items != 1)
         throw pgf_error("couldn't write to the output file");
 }
@@ -90,7 +89,7 @@ void PgfWriter::write_uint(uint64_t u)
 		if (u == 0) {
             size_t n_items = fwrite(&b, sizeof(b), 1, out);
             if (ferror(out))
-                throw pgf_systemerror(ferror(out), filepath);
+                throw pgf_error("an error occured while writing out the grammar");
             if (n_items != 1)
                 throw pgf_error("couldn't write to the output file");
 
@@ -100,7 +99,7 @@ void PgfWriter::write_uint(uint64_t u)
 
             size_t n_items = fwrite(&b, sizeof(b), 1, out);
             if (ferror(out))
-                throw pgf_systemerror(ferror(out), filepath);
+                throw pgf_error("an error occured while writing out the grammar");
             if (n_items != 1)
                 throw pgf_error("couldn't write to the output file");
 		}
@@ -112,7 +111,7 @@ void PgfWriter::write_name(PgfText *text)
 	write_len(text->size);
     size_t n_items = fwrite(&text->text, text->size, 1, out);
     if (ferror(out))
-        throw pgf_systemerror(ferror(out), filepath);
+        throw pgf_error("an error occured while writing out the grammar");
     if (n_items != 1)
         throw pgf_error("couldn't write to the output file");
 }
@@ -128,7 +127,7 @@ void PgfWriter::write_text(PgfText *text)
 	write_len(len);
     size_t n_items = fwrite(&text->text, text->size, 1, out);
     if (ferror(out))
-        throw pgf_systemerror(ferror(out), filepath);
+        throw pgf_error("an error occured while writing out the grammar");
     if (n_items != 1)
         throw pgf_error("couldn't write to the output file");
 }
diff --git a/src/runtime/c/pgf/writer.h b/src/runtime/c/pgf/writer.h
index 6cde9d3f9..fa0f246ad 100644
--- a/src/runtime/c/pgf/writer.h
+++ b/src/runtime/c/pgf/writer.h
@@ -4,7 +4,7 @@
 class PGF_INTERNAL_DECL PgfWriter
 {
 public:
-    PgfWriter(FILE *out, const char *filepath);
+    PgfWriter(FILE *out);
 
     void write_uint8(uint8_t b);
     void write_u16be(uint16_t u);
@@ -49,7 +49,6 @@ private:
     void write_namespace_helper(Namespace<V> nmsp, void (PgfWriter::*write_value)(ref<V>));
 
     FILE *out;
-    const char* filepath;
     ref<PgfAbstr> abstract;
 };