diff --git a/moo/kernel/IO.moo b/moo/kernel/IO.moo
index f24077c..a74e4d5 100644
--- a/moo/kernel/IO.moo
+++ b/moo/kernel/IO.moo
@@ -13,9 +13,9 @@ class FileAccessor(InputOutputStud) from "io.file"
 	{
 		//O_RDONLY := 0,
 		//O_WRONLY := 1
-		O_RDONLY from "io.file.O_RDONLY",
-		O_WRONLY from "io.file.O_WRONLY",
-		O_RDWR   from "io.file.O_RDWR"
+		O_RDONLY from "O_RDONLY",
+		O_WRONLY from "O_WRONLY",
+		O_RDWR   from "O_RDWR"
 	}
 
 	method(#primitive,#lenient) _open: path flags: flags.
diff --git a/moo/lib/comp.c b/moo/lib/comp.c
index 3df0325..f091714 100644
--- a/moo/lib/comp.c
+++ b/moo/lib/comp.c
@@ -10195,6 +10195,9 @@ static int __compile_pooldic_definition (moo_t* moo)
 		if (TOKEN_TYPE(moo) == MOO_IOTOK_IDENT && is_token_word(moo, VOCA_FROM))
 		{
 			moo_pvbase_t* pvbase;
+			moo_cunit_class_t* pcc;
+			moo_oow_t savedlen;
+
 			/*
 			 * pooldic X {
 			 *    O_RDONLY := 0,
@@ -10202,20 +10205,46 @@ static int __compile_pooldic_definition (moo_t* moo)
 			 * }
 			 */
 
-			/* TODO: check if this pooldic definition is nested inside a class */
-/* TODO: make it more robust */
-			GET_TOKEN (moo);
-			if (TOKEN_TYPE(moo) != MOO_IOTOK_STRLIT)
+			if (!pd->cunit_parent || pd->cunit_parent->cunit_type != MOO_CUNIT_CLASS)
 			{
-				moo_setsynerrbfmt (moo, MOO_SYNERR_STRING, TOKEN_LOC(moo), TOKEN_NAME(moo), "primitive value name to import expected");
+				moo_setsynerrbfmt (moo, MOO_SYNERR_PVIMPBANNED, TOKEN_LOC(moo), TOKEN_NAME(moo), "primitive value from module not allowed in non-nested pooldic");
 				goto oops;
 			}
 
-			pvbase = moo_querymodpv(moo, TOKEN_NAME_PTR(moo), TOKEN_NAME_LEN(moo), MOO_NULL);
+			pcc = (moo_cunit_class_t*)pd->cunit_parent;
+			if (pcc->modname.len <= 0)
+			{
+				moo_setsynerrbfmt (moo, MOO_SYNERR_PVIMPBANNED, TOKEN_LOC(moo), TOKEN_NAME(moo), "primitive value from module not allowed without module from class");
+				goto oops;
+			}
+
+			GET_TOKEN (moo);
+			if (TOKEN_TYPE(moo) != MOO_IOTOK_STRLIT)
+			{
+				moo_setsynerr (moo, MOO_SYNERR_PVIDINVAL, TOKEN_LOC(moo), TOKEN_NAME(moo));
+				goto oops;
+			}
+
+			if (moo_rfind_oochar(TOKEN_NAME_PTR(moo), TOKEN_NAME_LEN(moo), '.'))
+			{
+				moo_setsynerrbfmt (moo, MOO_SYNERR_PVIDINVAL, TOKEN_LOC(moo), TOKEN_NAME(moo), "primitive value identifier disallowed to have period");
+				goto oops;
+			}
+
+			/* append the primitive value name to the module name of the parent class.
+			 * it is restored to the saved length after module query for primitive value */
+			savedlen = pcc->modname.len;
+			if (copy_string_to (moo, TOKEN_NAME(moo), &pcc->modname, &pcc->modname_capa, 1, '.') <= -1)
+			{
+				pcc->modname.len = savedlen;
+				goto oops;
+			}
+			pvbase = moo_querymodpv(moo, pcc->modname.ptr, pcc->modname.len, MOO_NULL);
+			pcc->modname.len = savedlen;
 			if (!pvbase)
 			{
-				/* TODO: backup error message and use it */
-				moo_setsynerrbfmt (moo, MOO_SYNERR_STRING, TOKEN_LOC(moo), TOKEN_NAME(moo), "primitive value name unknown");
+				const moo_ooch_t* oldmsg = moo_backuperrmsg(moo);
+				moo_setsynerrbfmt (moo, MOO_SYNERR_PVIDINVAL, TOKEN_LOC(moo), TOKEN_NAME(moo), "wrong primitive value identifier - %js", oldmsg);
 				goto oops;
 			}
 
@@ -10234,8 +10263,11 @@ static int __compile_pooldic_definition (moo_t* moo)
 					break;
 				}
 
+			/*	case MOO_PV_STR:
+			*/
+
 				default:
-					moo_setsynerrbfmt (moo, MOO_SYNERR_STRING, TOKEN_LOC(moo), TOKEN_NAME(moo), "unsupported pvtype");
+					moo_setsynerrbfmt (moo, MOO_SYNERR_STRING, TOKEN_LOC(moo), TOKEN_NAME(moo), "unsupported primitive value type - %d", pvbase->type);
 					goto oops;
 			}
 
diff --git a/moo/lib/err.c b/moo/lib/err.c
index 0099215..fb97a23 100644
--- a/moo/lib/err.c
+++ b/moo/lib/err.c
@@ -139,18 +139,20 @@ static moo_ooch_t synerrstr_63[] = {'i','n','s','t','r','u','c','t','i','o','n',
 static moo_ooch_t synerrstr_64[] = {'w','r','o','n','g',' ','p','r','i','m','i','t','i','v','e',' ','f','u','n','c','t','i','o','n',' ','n','u','m','b','e','r','\0'};
 static moo_ooch_t synerrstr_65[] = {'w','r','o','n','g',' ','p','r','i','m','i','t','i','v','e',' ','f','u','n','c','t','i','o','n',' ','i','d','e','n','t','i','f','i','e','r','\0'};
 static moo_ooch_t synerrstr_66[] = {'w','r','o','n','g',' ','p','r','i','m','i','t','i','v','e',' ','f','u','n','c','t','i','o','n',' ','a','r','g','u','m','e','n','t',' ','d','e','f','i','n','i','t','i','o','n','\0'};
-static moo_ooch_t synerrstr_67[] = {'f','a','i','l','e','d',' ','t','o',' ','i','m','p','o','r','t',' ','m','o','d','u','l','e','\0'};
-static moo_ooch_t synerrstr_68[] = {'#','i','n','c','l','u','d','e',' ','e','r','r','o','r','\0'};
-static moo_ooch_t synerrstr_69[] = {'w','r','o','n','g',' ','p','r','a','g','m','a',' ','n','a','m','e','\0'};
-static moo_ooch_t synerrstr_70[] = {'w','r','o','n','g',' ','n','a','m','e','s','p','a','c','e',' ','n','a','m','e','\0'};
-static moo_ooch_t synerrstr_71[] = {'w','r','o','n','g',' ','p','o','o','l','d','i','c',' ','i','m','p','o','r','t',' ','n','a','m','e','\0'};
-static moo_ooch_t synerrstr_72[] = {'d','u','p','l','i','c','a','t','e',' ','p','o','o','l','d','i','c',' ','i','m','p','o','r','t',' ','n','a','m','e','\0'};
-static moo_ooch_t synerrstr_73[] = {'l','i','t','e','r','a','l',' ','e','x','p','e','c','t','e','d','\0'};
-static moo_ooch_t synerrstr_74[] = {'b','r','e','a','k',' ','o','r',' ','c','o','n','t','i','n','u','e',' ','n','o','t',' ','w','i','t','h','i','n',' ','a',' ','l','o','o','p','\0'};
-static moo_ooch_t synerrstr_75[] = {'b','r','e','a','k',' ','o','r',' ','c','o','n','t','i','n','u','e',' ','w','i','t','h','i','n',' ','a',' ','b','l','o','c','k','\0'};
-static moo_ooch_t synerrstr_76[] = {'w','h','i','l','e',' ','e','x','p','e','c','t','e','d','\0'};
-static moo_ooch_t synerrstr_77[] = {'i','n','v','a','l','i','d',' ','g','o','t','o',' ','t','a','r','g','e','t','\0'};
-static moo_ooch_t synerrstr_78[] = {'l','a','b','e','l',' ','a','t',' ','e','n','d','\0'};
+static moo_ooch_t synerrstr_67[] = {'w','r','o','n','g',' ','p','r','i','m','i','t','i','v','e',' ','v','a','l','u','e',' ','i','d','e','n','t','i','f','i','e','r','\0'};
+static moo_ooch_t synerrstr_68[] = {'p','r','i','m','i','t','i','v','e',' ','v','a','l','u','e',' ','l','o','a','d',' ','f','r','o','m',' ','m','o','d','u','l','e',' ','n','o','t',' ','a','l','l','o','w','e','d','\0'};
+static moo_ooch_t synerrstr_69[] = {'f','a','i','l','e','d',' ','t','o',' ','i','m','p','o','r','t',' ','m','o','d','u','l','e','\0'};
+static moo_ooch_t synerrstr_70[] = {'#','i','n','c','l','u','d','e',' ','e','r','r','o','r','\0'};
+static moo_ooch_t synerrstr_71[] = {'w','r','o','n','g',' ','p','r','a','g','m','a',' ','n','a','m','e','\0'};
+static moo_ooch_t synerrstr_72[] = {'w','r','o','n','g',' ','n','a','m','e','s','p','a','c','e',' ','n','a','m','e','\0'};
+static moo_ooch_t synerrstr_73[] = {'w','r','o','n','g',' ','p','o','o','l','d','i','c',' ','i','m','p','o','r','t',' ','n','a','m','e','\0'};
+static moo_ooch_t synerrstr_74[] = {'d','u','p','l','i','c','a','t','e',' ','p','o','o','l','d','i','c',' ','i','m','p','o','r','t',' ','n','a','m','e','\0'};
+static moo_ooch_t synerrstr_75[] = {'l','i','t','e','r','a','l',' ','e','x','p','e','c','t','e','d','\0'};
+static moo_ooch_t synerrstr_76[] = {'b','r','e','a','k',' ','o','r',' ','c','o','n','t','i','n','u','e',' ','n','o','t',' ','w','i','t','h','i','n',' ','a',' ','l','o','o','p','\0'};
+static moo_ooch_t synerrstr_77[] = {'b','r','e','a','k',' ','o','r',' ','c','o','n','t','i','n','u','e',' ','w','i','t','h','i','n',' ','a',' ','b','l','o','c','k','\0'};
+static moo_ooch_t synerrstr_78[] = {'w','h','i','l','e',' ','e','x','p','e','c','t','e','d','\0'};
+static moo_ooch_t synerrstr_79[] = {'i','n','v','a','l','i','d',' ','g','o','t','o',' ','t','a','r','g','e','t','\0'};
+static moo_ooch_t synerrstr_80[] = {'l','a','b','e','l',' ','a','t',' ','e','n','d','\0'};
 static moo_ooch_t* synerrstr[] =
 {
 	synerrstr_0, synerrstr_1, synerrstr_2, synerrstr_3, synerrstr_4, synerrstr_5, synerrstr_6, synerrstr_7,
@@ -162,7 +164,8 @@ static moo_ooch_t* synerrstr[] =
 	synerrstr_48, synerrstr_49, synerrstr_50, synerrstr_51, synerrstr_52, synerrstr_53, synerrstr_54, synerrstr_55,
 	synerrstr_56, synerrstr_57, synerrstr_58, synerrstr_59, synerrstr_60, synerrstr_61, synerrstr_62, synerrstr_63,
 	synerrstr_64, synerrstr_65, synerrstr_66, synerrstr_67, synerrstr_68, synerrstr_69, synerrstr_70, synerrstr_71,
-	synerrstr_72, synerrstr_73, synerrstr_74, synerrstr_75, synerrstr_76, synerrstr_77, synerrstr_78 
+	synerrstr_72, synerrstr_73, synerrstr_74, synerrstr_75, synerrstr_76, synerrstr_77, synerrstr_78, synerrstr_79,
+	synerrstr_80 
 };
 #endif
 /* END: GENERATED WITH generr.moo */
diff --git a/moo/lib/moo.h b/moo/lib/moo.h
index df19569..0475154 100644
--- a/moo/lib/moo.h
+++ b/moo/lib/moo.h
@@ -1971,6 +1971,8 @@ enum moo_synerrnum_t
 	MOO_SYNERR_PFNUMINVAL,      /* wrong primitive function number */
 	MOO_SYNERR_PFIDINVAL,       /* wrong primitive function identifier */
 	MOO_SYNERR_PFARGDEFINVAL,   /* wrong primitive function argument definition */
+	MOO_SYNERR_PVIDINVAL,       /* wrong primitive value identifier */
+	MOO_SYNERR_PVIMPBANNED,     /* primitive value load from module not allowed */
 	MOO_SYNERR_MODIMPFAIL,      /* failed to import module */
 	MOO_SYNERR_INCLUDE,         /* #include error */
 	MOO_SYNERR_PRAGMAINVAL,     /* wrong pragma name */