diff --git a/b2/bom.c b/b2/bom.c
index 4fe7820..144025b 100644
--- a/b2/bom.c
+++ b/b2/bom.c
@@ -46,7 +46,7 @@ struct bom *bom_parse_line(const char *s)
 		s++;
 	for (t = s+1; *t && !isspace(*t); t++);
 	if (!*t)
-		yyerror("invalid BOM record (1)\n");
+		yyerror("invalid BOM record");
 
 	ref = unique_n(s, t-s);
 	if (bom_find(ref))
@@ -86,3 +86,16 @@ struct bom *bom_parse_line(const char *s)
 	}
 	return b;
 }
+
+
+void bom_set_sym(const char *ref, const char *sym)
+{
+	struct bom *b;
+
+	b = bom_find(ref);
+	if (!b)
+		yyerrorf("cannot find component reference \"%s\"", ref);
+	if (b->sym)
+		yyerrorf("symbol is already set in \"%s\"", ref);
+	b->sym = sym;
+}
diff --git a/b2/bom.h b/b2/bom.h
index c8de71c..1315339 100644
--- a/b2/bom.h
+++ b/b2/bom.h
@@ -30,5 +30,6 @@ extern int n_bom;
 
 
 struct bom *bom_parse_line(const char *s);
+void bom_set_sym(const char *ref, const char *sym);
 
 #endif /* !BOM_H */
diff --git a/b2/boom.c b/b2/boom.c
index 02153f0..5b9257b 100644
--- a/b2/boom.c
+++ b/b2/boom.c
@@ -83,6 +83,7 @@ static void usage(const char *name)
 "  -p  providers\n"
 "  -s  substitutions\n"
 "  -b  KiCad eeschema BOM\n"
+"  -X  symbols (BOM supplement)\n"
 "  -q var=value ...  run substitutions with the specified inputs\n"
 "  -Q var=value ...  run substitutions and then do parametric search\n"
     , name);
@@ -110,6 +111,8 @@ int main(int argc, char **argv)
 				process = parse_substitutions;
 			else if (!strcmp(argv[i], "-b"))
 				process = parse_kicad_bom;
+			else if (!strcmp(argv[i], "-X"))
+				process = parse_symbols;
 			else if (!strcmp(argv[i], "-q"))
 				process = add_var;
 			else if (!strcmp(argv[i], "-Q")) {
diff --git a/b2/lang.h b/b2/lang.h
index 78f0f04..fa1256e 100644
--- a/b2/lang.h
+++ b/b2/lang.h
@@ -29,6 +29,7 @@ void parse_currencies(const char *name);
 void parse_providers(const char *name);
 void parse_substitutions(const char *name);
 void parse_kicad_bom(const char *name);
+void parse_symbols(const char *name);
 
 void yywarnf(const char *fmt, ...);
 void __attribute__((noreturn)) yyerrorf(const char *fmt, ...);
diff --git a/b2/lang.l b/b2/lang.l
index 7941d54..97ae698 100644
--- a/b2/lang.l
+++ b/b2/lang.l
@@ -97,6 +97,12 @@ void parse_substitutions(const char *name)
 	do_parse(name, START_SUBST, 0, 1);
 }
 
+
+void parse_symbols(const char *name)
+{
+	do_parse(name, START_SYMBOLS, 1, 0);
+}
+
 %}
 
 
diff --git a/b2/lang.y b/b2/lang.y
index 1055726..0a0b7f7 100644
--- a/b2/lang.y
+++ b/b2/lang.y
@@ -102,6 +102,7 @@ static struct subst *parse_jump(const char *keyword, const char *target)
 
 %token			START_HIERARCHY START_CHAR START_INVENTORY
 %token			START_EXCHANGE START_PROVIDERS START_SUBST START_BOM
+%token			START_SYMBOLS
 %token			BOM_EESCHEMA
 %token			TOK_LE TOK_GE TOK_NL
 %token	<s>		WORD PATTERN
@@ -140,6 +141,7 @@ all:
 			substitutions = $2;
 		}
 	| START_BOM bom
+	| START_SYMBOLS symbols
 	;
 
 
@@ -669,3 +671,19 @@ bom:
 		 * bom.c
 		 */
 	;
+
+
+/* ----- Symbols (BOM supplement) ------------------------------------------ */
+
+
+symbols:
+	| TOK_NL
+	| symbol symbols
+	;
+
+symbol:
+	WORD WORD TOK_NL
+		{
+			bom_set_sym($1, $2);
+		}
+	;