diff --git a/core/asm/lex_test.go b/core/asm/lex_test.go
index 6b8bd3d740..53e05fbbba 100644
--- a/core/asm/lex_test.go
+++ b/core/asm/lex_test.go
@@ -60,6 +60,10 @@ func TestLexer(t *testing.T) {
 			input:  "0123abc",
 			tokens: []token{{typ: lineStart}, {typ: number, text: "0123"}, {typ: element, text: "abc"}, {typ: eof}},
 		},
+		{
+			input:  "00123abc",
+			tokens: []token{{typ: lineStart}, {typ: number, text: "00123"}, {typ: element, text: "abc"}, {typ: eof}},
+		},
 		{
 			input:  "@foo",
 			tokens: []token{{typ: lineStart}, {typ: label, text: "foo"}, {typ: eof}},
diff --git a/core/asm/lexer.go b/core/asm/lexer.go
index 9eb8f914ac..21cc8c4658 100644
--- a/core/asm/lexer.go
+++ b/core/asm/lexer.go
@@ -254,7 +254,7 @@ func lexInsideString(l *lexer) stateFn {
 
 func lexNumber(l *lexer) stateFn {
 	acceptance := Numbers
-	if l.accept("0") || l.accept("xX") {
+	if l.accept("xX") {
 		acceptance = HexadecimalNumbers
 	}
 	l.acceptRun(acceptance)