diff --git a/source/toy_lexer.c b/source/toy_lexer.c
index a7bd4ac..c77df7c 100644
--- a/source/toy_lexer.c
+++ b/source/toy_lexer.c
@@ -141,12 +141,12 @@ static Toy_Token makeToken(Toy_Lexer* lexer, Toy_TokenType type) {
 static Toy_Token makeIntegerOrFloat(Toy_Lexer* lexer) {
 	Toy_TokenType type = TOY_TOKEN_LITERAL_INTEGER; //what am I making?
 
-	while(isDigit(lexer)) advance(lexer);
+	while(isDigit(lexer) || peek(lexer) == '_') advance(lexer);
 
 	if (peek(lexer) == '.' && (peekNext(lexer) >= '0' && peekNext(lexer) <= '9')) { //BUGFIX: peekNext == digit
 		type = TOY_TOKEN_LITERAL_FLOAT;
 		advance(lexer);
-		while(isDigit(lexer)) advance(lexer);
+		while(isDigit(lexer) || peek(lexer) == '_') advance(lexer);
 	}
 
 	Toy_Token token;
diff --git a/source/toy_parser.c b/source/toy_parser.c
index a559da1..94f2bf8 100644
--- a/source/toy_parser.c
+++ b/source/toy_parser.c
@@ -508,6 +508,22 @@ static Toy_Opcode unary(Toy_Parser* parser, Toy_ASTNode** nodeHandle) {
 	return TOY_OP_EOF;
 }
 
+static char* removeChar(char* lexeme, int length, char c) {
+	int resPos = 0;
+	char* result = TOY_ALLOCATE(char, length + 1);
+
+	for (int i = 0; i < length; i++) {
+		if (lexeme[i] == c) {
+			continue;
+		}
+
+		result[resPos++] = lexeme[i];
+	}
+
+	result[resPos] = '\0';
+	return result;
+}
+
 static Toy_Opcode atomic(Toy_Parser* parser, Toy_ASTNode** nodeHandle) {
 	switch(parser->previous.type) {
 		case TOY_TOKEN_NULL:
@@ -524,14 +540,18 @@ static Toy_Opcode atomic(Toy_Parser* parser, Toy_ASTNode** nodeHandle) {
 
 		case TOY_TOKEN_LITERAL_INTEGER: {
 			int value = 0;
-			sscanf(parser->previous.lexeme, "%d", &value);
+			char* lexeme = removeChar(parser->previous.lexeme, parser->previous.length, '_');
+			sscanf(lexeme, "%d", &value);
+			TOY_FREE_ARRAY(char, lexeme, parser->previous.length + 1);
 			Toy_emitASTNodeLiteral(nodeHandle, TOY_TO_INTEGER_LITERAL(value));
 			return TOY_OP_EOF;
 		}
 
 		case TOY_TOKEN_LITERAL_FLOAT: {
 			float value = 0;
-			sscanf(parser->previous.lexeme, "%f", &value);
+			char* lexeme = removeChar(parser->previous.lexeme, parser->previous.length, '_');
+			sscanf(lexeme, "%f", &value);
+			TOY_FREE_ARRAY(char, lexeme, parser->previous.length + 1);
 			Toy_emitASTNodeLiteral(nodeHandle, TOY_TO_FLOAT_LITERAL(value));
 			return TOY_OP_EOF;
 		}
diff --git a/test/test_parser.c b/test/test_parser.c
index 99882d5..de3cdd3 100644
--- a/test/test_parser.c
+++ b/test/test_parser.c
@@ -121,6 +121,44 @@ int main() {
 		Toy_freeParser(&parser);
 	}
 
+	{
+		//test parsing of underscored numbers
+		char* source = "print 1_000_000;";
+
+		//test parsing
+		Toy_Lexer lexer;
+		Toy_Parser parser;
+		Toy_initLexer(&lexer, source);
+		Toy_initParser(&parser, &lexer);
+
+		Toy_ASTNode* node = Toy_scanParser(&parser);
+
+		//inspect the node
+		if (node == NULL) {
+			fprintf(stderr, TOY_CC_ERROR "ERROR: ASTNode is null\n" TOY_CC_RESET);
+			return -1;
+		}
+
+		if (node->type != TOY_AST_NODE_UNARY || node->unary.opcode != TOY_OP_PRINT) {
+			fprintf(stderr, TOY_CC_ERROR "ERROR: ASTNode is not a unary print instruction\n" TOY_CC_RESET);
+			return -1;
+		}
+
+		if (node->unary.child->type != TOY_AST_NODE_LITERAL || !TOY_IS_INTEGER(node->unary.child->atomic.literal)) {
+			fprintf(stderr, TOY_CC_ERROR "ERROR: ASTNode to be printed is not a string literal\n" TOY_CC_RESET);
+			return -1;
+		}
+
+		if (TOY_AS_INTEGER(node->unary.child->atomic.literal) != 1000000) {
+			fprintf(stderr, TOY_CC_ERROR "ERROR: ASTNode to be printed is not the correct value, found: %d\n" TOY_CC_RESET, TOY_AS_INTEGER(node->unary.child->atomic.literal));
+			return -1;
+		}
+
+		//cleanup
+		Toy_freeASTNode(node);
+		Toy_freeParser(&parser);
+	}
+
 	printf(TOY_CC_NOTICE "All good\n" TOY_CC_RESET);
 	return 0;
 }