diff --git a/src/libponyc/codegen/genmatch.c b/src/libponyc/codegen/genmatch.c
index fc4023ce59..7fba3a45cd 100644
--- a/src/libponyc/codegen/genmatch.c
+++ b/src/libponyc/codegen/genmatch.c
@@ -804,7 +804,7 @@ LLVMValueRef gen_match(compile_t* c, ast_t* ast)
     ast_t* pattern_type = deferred_reify(reify, ast_type(the_case), c->opt);
     bool ok = true;
 
-    matchtype_t match = is_matchtype(match_type, pattern_type, NULL, c->opt);
+    matchtype_t match = is_matchtype_with_consumed_pattern(match_type, pattern_type, NULL, c->opt);
 
     ast_free_unattached(pattern_type);
 
diff --git a/src/libponyc/codegen/gentrace.c b/src/libponyc/codegen/gentrace.c
index f0f381178e..b625abf494 100644
--- a/src/libponyc/codegen/gentrace.c
+++ b/src/libponyc/codegen/gentrace.c
@@ -546,7 +546,7 @@ static int trace_cap_nominal(pass_opt_t* opt, ast_t* type, ast_t* orig,
   // val and tag in that order.
   if(orig_cap == TK_ISO)
   {
-    if(is_astype(orig, type, NULL, opt) == MATCHTYPE_ACCEPT)
+    if(is_matchtype(orig, type, NULL, opt) == MATCHTYPE_ACCEPT)
     {
       return PONY_TRACE_MUTABLE;
     } else {
@@ -556,7 +556,7 @@ static int trace_cap_nominal(pass_opt_t* opt, ast_t* type, ast_t* orig,
 
   if(ast_id(cap) == TK_VAL)
   {
-    if(is_astype(orig, type, NULL, opt) == MATCHTYPE_ACCEPT)
+    if(is_matchtype(orig, type, NULL, opt) == MATCHTYPE_ACCEPT)
     {
       ast_setid(cap, orig_cap);
       return PONY_TRACE_IMMUTABLE;
@@ -568,7 +568,7 @@ static int trace_cap_nominal(pass_opt_t* opt, ast_t* type, ast_t* orig,
   pony_assert(ast_id(cap) == TK_TAG);
 
   int ret = -1;
-  if(is_astype(orig, type, NULL, opt) == MATCHTYPE_ACCEPT)
+  if(is_matchtype(orig, type, NULL, opt) == MATCHTYPE_ACCEPT)
     ret = PONY_TRACE_OPAQUE;
 
   ast_setid(cap, orig_cap);
diff --git a/src/libponyc/expr/match.c b/src/libponyc/expr/match.c
index 3dcb12f985..13680afd4d 100644
--- a/src/libponyc/expr/match.c
+++ b/src/libponyc/expr/match.c
@@ -507,7 +507,7 @@ bool expr_case(pass_opt_t* opt, ast_t* ast)
   bool ok = true;
   errorframe_t info = NULL;
 
-  switch(is_matchtype(match_type, pattern_type, &info, opt))
+  switch(is_matchtype_with_consumed_pattern(match_type, pattern_type, &info, opt))
   {
     case MATCHTYPE_ACCEPT:
       break;
diff --git a/src/libponyc/expr/operator.c b/src/libponyc/expr/operator.c
index 02f73395b6..4c8eda1d5f 100644
--- a/src/libponyc/expr/operator.c
+++ b/src/libponyc/expr/operator.c
@@ -551,7 +551,7 @@ static bool add_as_type(pass_opt_t* opt, ast_t* ast, ast_t* expr,
 
       ast_t* expr_type = ast_type(expr);
       errorframe_t info = NULL;
-      matchtype_t is_match = is_astype(expr_type, type, &info, opt);
+      matchtype_t is_match = is_matchtype(expr_type, type, &info, opt);
       if(is_match == MATCHTYPE_DENY_CAP)
       {
         errorframe_t frame = NULL;
diff --git a/src/libponyc/type/matchtype.c b/src/libponyc/type/matchtype.c
index 90e6218a79..db96c4ca8d 100644
--- a/src/libponyc/type/matchtype.c
+++ b/src/libponyc/type/matchtype.c
@@ -929,6 +929,12 @@ static matchtype_t is_x_match_x(ast_t* operand, ast_t* pattern,
 
 matchtype_t is_matchtype(ast_t* operand, ast_t* pattern, errorframe_t* errorf,
   pass_opt_t* opt)
+{
+  return is_x_match_x(operand, pattern, errorf, true, opt);
+}
+
+matchtype_t is_matchtype_with_consumed_pattern(ast_t* operand, ast_t* pattern, errorframe_t* errorf,
+  pass_opt_t* opt)
 {
   ast_t* consumed_pattern = consume_type(pattern, TK_NONE, false);
   if (consumed_pattern == NULL)
@@ -942,9 +948,3 @@ matchtype_t is_matchtype(ast_t* operand, ast_t* pattern, errorframe_t* errorf,
 
   return rslt;
 }
-
-matchtype_t is_astype(ast_t* operand, ast_t* pattern, errorframe_t* errorf,
-  pass_opt_t* opt)
-{
-  return is_x_match_x(operand, pattern, errorf, true, opt);
-}
diff --git a/src/libponyc/type/matchtype.h b/src/libponyc/type/matchtype.h
index 9f3ef536e6..9396a42d84 100644
--- a/src/libponyc/type/matchtype.h
+++ b/src/libponyc/type/matchtype.h
@@ -45,11 +45,9 @@ matchtype_t is_matchtype(ast_t* operand, ast_t* pattern, errorframe_t* errorf,
   pass_opt_t* opt);
 
 /**
- * Same as is_matchtype() but specifically designed to work with `as` which
- * under the steed model, needs to act differently than matchwith respect
- * to iso.
+ * Same as is_matchtype() but it consumes the pattern type and then sees if a match works. Used in match.c and genmatch.c to close issue #4579.
  */
-matchtype_t is_astype(ast_t* operand, ast_t* pattern, errorframe_t* errorf,
+matchtype_t is_matchtype_with_consumed_pattern(ast_t* operand, ast_t* pattern, errorframe_t* errorf,
   pass_opt_t* opt);
 
 PONY_EXTERN_C_END