diff --git a/etk-asm/src/parse/asm.pest b/etk-asm/src/parse/asm.pest
index d814eb3b..a3ae55e7 100644
--- a/etk-asm/src/parse/asm.pest
+++ b/etk-asm/src/parse/asm.pest
@@ -37,9 +37,11 @@ decimal = @{ ASCII_DIGIT+ }
 hex = @{ "0x" ~ ASCII_HEX_DIGIT ~ ASCII_HEX_DIGIT+ }
 number = _{ binary | octal | hex | decimal }
 
+no_spaces_in_selector = @{ !WHITESPACE ~ ASCII_ALPHANUMERIC }
+no_spaces_before_selector = @{ !WHITESPACE ~ ASCII_ALPHA }
 selector = { "selector(\"" ~ function_declaration ~ "\")" }
-function_declaration = { function_name ~ "(" ~ ASCII_ALPHANUMERIC* ~ ("," ~ ASCII_ALPHANUMERIC+)* ~ ")" }
-function_name = @{ ( ASCII_ALPHA | "_" ) ~ ( ASCII_ALPHANUMERIC | "_" )* }
+function_declaration = { function_name ~ "(" ~ no_spaces_in_selector* ~ ("," ~ no_spaces_in_selector+)* ~ ")" }
+function_name = { (no_spaces_before_selector | "_" ) ~ ( no_spaces_in_selector | "_" )* }
 
 label = @{ ASCII_ALPHA ~ (ASCII_ALPHANUMERIC | "_")* }
 label_defn = { label ~ ":" }