diff --git a/ee.c b/ee.c
index 40cff2f..cdce3e5 100644
--- a/ee.c
+++ b/ee.c
@@ -64,7 +64,7 @@ arrity(const char query){
 
 
 double 
-evaluate(STACK* target_stack, ch operator){
+evaluate(STACK* target_stack, char operator){
     /*
      * If target_stack is a pointer to a STACK and operator is
      * a char corresponding to a supported operator,