diff --git a/docs/metadesk_reference.mdesk b/docs/metadesk_reference.mdesk
index 4ed931e..962443e 100644
--- a/docs/metadesk_reference.mdesk
+++ b/docs/metadesk_reference.mdesk
@@ -949,6 +949,7 @@ main:
 @see(MD_String8Node)
 @see(MD_String8)
 @func MD_S8ListPush: {
+    arena: *MD_Arena,
     list: *MD_String8List,
     string: MD_String8,
 };
@@ -988,6 +989,7 @@ main:
 @see(MD_String8Node)
 @see(MD_S8Split)
 @func MD_S8ListJoin: {
+    arena: *MD_Arena,
     list: MD_String8List,
     join: *MD_StringJoin,
     return: MD_String8,
@@ -1001,6 +1003,7 @@ main:
 
 @send(Strings)
 @func MD_S8Stylize: {
+    arena: *MD_Arena,
     string: MD_String8,
     word_style: MD_IdentifierStyle,
     separator: MD_String8,
@@ -1045,6 +1048,7 @@ main:
 @send(Nodes)
 @doc("Builds a string list for all bits set in @code 'flags', with each string being the name of one of the flags that is set.")
 @func MD_StringListFromNodeFlags: {
+    arena: *MD_Arena,
     flags: MD_NodeFlags,
     return: MD_String8List,
 };
@@ -1692,6 +1696,7 @@ MD_ParseWholeFile:
 @see(MD_CmdLineB32FromString)
 @func MD_MakeCmdLineFromOptions:
 {
+    arena: *MD_Arena,
     options: MD_String8List;
     return: MD_CmdLine;
 }
diff --git a/samples/output_parse/output_parse.c b/samples/output_parse/output_parse.c
index 4842827..fe9fb8f 100644
--- a/samples/output_parse/output_parse.c
+++ b/samples/output_parse/output_parse.c
@@ -2,6 +2,8 @@
 #include "md.h"
 #include "md.c"
 
+static MD_Arena *arena = 0;
+
 #define INDENT_SPACES 2
 static void Print(FILE* file, int indent_count, char* fmt, ...) {
     for(int i = 0; i < indent_count*INDENT_SPACES; i += 1)
@@ -31,7 +33,7 @@ static void PrintNode(MD_Node* node, FILE* file, int indent_count) {
     
     Print(file, indent_count+1, "Flags: %s,\n", binary_flags);
     Print(file, indent_count+1, "Flag Names: ", binary_flags);
-    MD_String8List flags_list = MD_StringListFromNodeFlags(node->flags);
+    MD_String8List flags_list = MD_StringListFromNodeFlags(arena, node->flags);
     
     MD_StringJoin join = MD_ZERO_STRUCT;
     join.mid = MD_S8CString(", ");
@@ -62,7 +64,7 @@ static void PrintNode(MD_Node* node, FILE* file, int indent_count) {
 
 int main(int argument_count, char **arguments)
 {
-    MD_Arena *arena = MD_ArenaNew(1ull << 40);
+    arena = MD_ArenaNew(1ull << 40);
     
     // NOTE(pmh): Parse all the files passed in via command line.
     MD_Node *list = MD_MakeList();
diff --git a/samples/static_site_generator/static_site_generator.c b/samples/static_site_generator/static_site_generator.c
index 930a9bf..f94113a 100644
--- a/samples/static_site_generator/static_site_generator.c
+++ b/samples/static_site_generator/static_site_generator.c
@@ -37,7 +37,8 @@ int main(int argument_count, char **arguments)
     arena = MD_ArenaNew(1ull << 40);
     
     //~ NOTE(rjf): Parse command line arguments.
-    MD_CmdLine cmdln = MD_MakeCmdLineFromOptions(MD_StringListFromArgCV(argument_count, arguments));
+    MD_String8List arg_list = MD_StringListFromArgCV(arena, argument_count, arguments);
+    MD_CmdLine cmdln = MD_MakeCmdLineFromOptions(arena, arg_list);
     MD_String8 site_info_path = MD_S8ListJoin(MD_CmdLineValuesFromString(cmdln, MD_S8Lit("siteinfo")), 0);
     MD_String8 page_dir_path = MD_S8ListJoin(MD_CmdLineValuesFromString(cmdln, MD_S8Lit("pagedir")), 0);
     if(!MD_CmdLineB32FromString(cmdln, MD_S8Lit("siteinfo")) ||
@@ -406,7 +407,8 @@ GeneratePageContent(MD_Map *index_table, SiteInfo *site_info, PageInfo *page_inf
         {
             MD_S8Lit("\n\n"),
         };
-        MD_String8List strlist = MD_S8Split(node->string, sizeof(splits)/sizeof(splits[0]), splits);
+        MD_String8List strlist = MD_S8Split(arena, node->string, sizeof(splits)/sizeof(splits[0]),
+                                            splits);
         
         for(MD_String8Node *strnode = strlist.first; strnode; strnode = strnode->next)
         {
diff --git a/samples/toy_language/toy_language.c b/samples/toy_language/toy_language.c
index 303c1e5..3f6854b 100644
--- a/samples/toy_language/toy_language.c
+++ b/samples/toy_language/toy_language.c
@@ -183,7 +183,8 @@ int main(int argument_count, char **arguments)
     MD_Arena *arena = MD_ArenaNew(1ull << 40);
     
     //- rjf: parse command line
-    MD_CmdLine cmdln = MD_MakeCmdLineFromOptions(MD_StringListFromArgCV(argument_count, arguments));
+    MD_String8List arg_list = MD_StringListFromArgCV(arena, argument_count, arguments);
+    MD_CmdLine cmdln = MD_MakeCmdLineFromOptions(arena, arg_list);
     
     //- rjf: parse all input files
     MD_Node *file_list = MD_MakeList();
diff --git a/source/md.c b/source/md.c
index 3a9226d..c1cc6ce 100644
--- a/source/md.c
+++ b/source/md.c
@@ -682,9 +682,9 @@ MD_S8Fmt(MD_Arena *arena, char *fmt, ...)
 }
 
 MD_FUNCTION_IMPL void
-MD_S8ListPush(MD_String8List *list, MD_String8 string)
+MD_S8ListPush(MD_Arena *arena, MD_String8List *list, MD_String8 string)
 {
-    MD_String8Node *node = MD_PushArray(MD_String8Node, 1);
+    MD_String8Node *node = MD_PushArrayAr(arena, MD_String8Node, 1);
     node->string = string;
     
     MD_QueuePush(list->first, list->last, node);
@@ -714,7 +714,7 @@ MD_S8ListConcat(MD_String8List *list, MD_String8List *to_push)
 }
 
 MD_FUNCTION_IMPL MD_String8List
-MD_S8Split(MD_String8 string, int split_count, MD_String8 *splits)
+MD_S8Split(MD_Arena *arena, MD_String8 string, int split_count, MD_String8 *splits)
 {
     MD_String8List list = MD_ZERO_STRUCT;
     
@@ -740,7 +740,7 @@ MD_S8Split(MD_String8 string, int split_count, MD_String8 *splits)
             if(match)
             {
                 MD_String8 split_string = MD_S8(string.str + split_start, i - split_start);
-                MD_S8ListPush(&list, split_string);
+                MD_S8ListPush(arena, &list, split_string);
                 split_start = i + splits[split_idx].size;
                 i += splits[split_idx].size - 1;
                 was_split = 1;
@@ -751,7 +751,7 @@ MD_S8Split(MD_String8 string, int split_count, MD_String8 *splits)
         if(was_split == 0 && i == string.size - 1)
         {
             MD_String8 split_string = MD_S8(string.str + split_start, i+1 - split_start);
-            MD_S8ListPush(&list, split_string);
+            MD_S8ListPush(arena, &list, split_string);
             break;
         }
     }
@@ -798,7 +798,8 @@ MD_S8ListJoin(MD_String8List list, MD_StringJoin *join_ptr)
 }
 
 MD_FUNCTION_IMPL MD_String8
-MD_S8Stylize(MD_String8 string, MD_IdentifierStyle word_style, MD_String8 separator)
+MD_S8Stylize(MD_Arena *arena, MD_String8 string, MD_IdentifierStyle word_style,
+             MD_String8 separator)
 {
     MD_String8 result = MD_ZERO_STRUCT;
     
@@ -833,7 +834,7 @@ MD_S8Stylize(MD_String8 string, MD_IdentifierStyle word_style, MD_String8 separa
                     word.size += 1;
                 }
                 making_word = 0;
-                MD_S8ListPush(&words, word);
+                MD_S8ListPush(arena, &words, word);
             }
             else
             {
@@ -1353,7 +1354,7 @@ MD_StringFromNodeKind(MD_NodeKind kind)
 }
 
 MD_FUNCTION_IMPL MD_String8List
-MD_StringListFromNodeFlags(MD_NodeFlags flags)
+MD_StringListFromNodeFlags(MD_Arena *arena, MD_NodeFlags flags)
 {
     // NOTE(rjf): @maintenance Must be kept in sync with MD_NodeFlags enum.
     static char *flag_cstrs[] =
@@ -1387,7 +1388,7 @@ MD_StringListFromNodeFlags(MD_NodeFlags flags)
     {
         if(flags & (1ull << i))
         {
-            MD_S8ListPush(&list, MD_S8CString(flag_cstrs[i]));
+            MD_S8ListPush(arena, &list, MD_S8CString(flag_cstrs[i]));
         }
     }
     return list;
@@ -2305,7 +2306,7 @@ MD_ParseOneNode(MD_Arena *arena, MD_String8 string, MD_u64 offset)
                     for(int i_byte = 0; i_byte < bad_token.raw_string.size; ++i_byte)
                     {
                         MD_u8 b = bad_token.raw_string.str[i_byte];
-                        MD_S8ListPush(&bytes, MD_CStyleHexStringFromU64(b, 1));
+                        MD_S8ListPush(arena, &bytes, MD_CStyleHexStringFromU64(b, 1));
                     }
                     
                     MD_StringJoin join = MD_ZERO_STRUCT;
@@ -2835,18 +2836,18 @@ MD_DebugOutputTree(FILE *file, MD_Node *node, int indent_spaces)
 //~ Command Line Argument Helper
 
 MD_FUNCTION MD_String8List
-MD_StringListFromArgCV(int argument_count, char **arguments)
+MD_StringListFromArgCV(MD_Arena *arena, int argument_count, char **arguments)
 {
     MD_String8List options = MD_ZERO_STRUCT;
     for(int i = 1; i < argument_count; i += 1)
     {
-        MD_S8ListPush(&options, MD_S8CString(arguments[i]));
+        MD_S8ListPush(arena, &options, MD_S8CString(arguments[i]));
     }
     return options;
 }
 
 MD_FUNCTION MD_CmdLine
-MD_MakeCmdLineFromOptions(MD_String8List options)
+MD_MakeCmdLineFromOptions(MD_Arena *arena, MD_String8List options)
 {
     MD_CmdLine cmdln = MD_ZERO_STRUCT;
     
@@ -2893,7 +2894,7 @@ MD_MakeCmdLineFromOptions(MD_String8List options)
             //- rjf: push first value
             if(first_value.size != 0)
             {
-                MD_S8ListPush(&option_values, first_value);
+                MD_S8ListPush(arena, &option_values, first_value);
             }
             
             //- rjf: scan next string values, add them to option values until we hit a lack
@@ -2912,7 +2913,7 @@ MD_MakeCmdLineFromOptions(MD_String8List options)
                         {
                             if(start != i)
                             {
-                                MD_S8ListPush(&option_values, MD_S8Substring(value_str, start, i));
+                                MD_S8ListPush(arena, &option_values, MD_S8Substring(value_str, start, i));
                             }
                             start = i+1;
                         }
@@ -2949,7 +2950,7 @@ MD_MakeCmdLineFromOptions(MD_String8List options)
         //- rjf: this argument is not an option, push it to regular inputs list.
         else
         {
-            MD_S8ListPush(&cmdln.inputs, n->string);
+            MD_S8ListPush(arena, &cmdln.inputs, n->string);
         }
     }
     
diff --git a/source/md.h b/source/md.h
index 797cfe7..50ef13b 100644
--- a/source/md.h
+++ b/source/md.h
@@ -761,12 +761,15 @@ MD_FUNCTION MD_String8     MD_S8Fmt(MD_Arena *arena, char *fmt, ...);
 
 #define MD_S8VArg(s) (int)(s).size, (s).str
 
-MD_FUNCTION void           MD_S8ListPush(MD_String8List *list, MD_String8 string);
+MD_FUNCTION void           MD_S8ListPush(MD_Arena *arena, MD_String8List *list,
+                                         MD_String8 string);
 MD_FUNCTION void           MD_S8ListConcat(MD_String8List *list, MD_String8List *to_push);
-MD_FUNCTION MD_String8List MD_S8Split(MD_String8 string, int split_count, MD_String8 *splits);
+MD_FUNCTION MD_String8List MD_S8Split(MD_Arena *arena, MD_String8 string, int split_count,
+                                      MD_String8 *splits);
 MD_FUNCTION MD_String8     MD_S8ListJoin(MD_String8List list, MD_StringJoin *join);
 
-MD_FUNCTION MD_String8     MD_S8Stylize(MD_String8 string, MD_IdentifierStyle word_style, MD_String8 separator);
+MD_FUNCTION MD_String8     MD_S8Stylize(MD_Arena *arena, MD_String8 string,
+                                        MD_IdentifierStyle style, MD_String8 separator);
 
 //~ Unicode Conversions
 
@@ -804,7 +807,7 @@ MD_FUNCTION MD_String8 MD_CStyleHexStringFromU64(MD_u64 x, MD_b32 caps);
 //~ Enum/Flag Strings
 
 MD_FUNCTION MD_String8     MD_StringFromNodeKind(MD_NodeKind kind);
-MD_FUNCTION MD_String8List MD_StringListFromNodeFlags(MD_NodeFlags flags);
+MD_FUNCTION MD_String8List MD_StringListFromNodeFlags(MD_Arena *arena, MD_NodeFlags flags);
 
 //~ Map Table Data Structure
 
@@ -896,8 +899,9 @@ MD_FUNCTION void MD_DebugOutputTree(FILE *file, MD_Node *node, int indent_spaces
 
 //~ Command Line Argument Helper
 
-MD_FUNCTION MD_String8List MD_StringListFromArgCV(int argument_count, char **arguments);
-MD_FUNCTION MD_CmdLine MD_MakeCmdLineFromOptions(MD_String8List options);
+MD_FUNCTION MD_String8List MD_StringListFromArgCV(MD_Arena *arena, int argument_count,
+                                                  char **arguments);
+MD_FUNCTION MD_CmdLine MD_MakeCmdLineFromOptions(MD_Arena *arena, MD_String8List options);
 MD_FUNCTION MD_String8List MD_CmdLineValuesFromString(MD_CmdLine cmdln, MD_String8 name);
 MD_FUNCTION MD_b32 MD_CmdLineB32FromString(MD_CmdLine cmdln, MD_String8 name);
 MD_FUNCTION MD_i64 MD_CmdLineI64FromString(MD_CmdLine cmdln, MD_String8 name);
diff --git a/tests/sanity_tests.c b/tests/sanity_tests.c
index 76e73d9..3c8615a 100644
--- a/tests/sanity_tests.c
+++ b/tests/sanity_tests.c
@@ -416,19 +416,23 @@ int main(void)
     Test("Style Strings")
     {
         {
-            MD_String8 str = MD_S8Stylize(MD_S8Lit("THIS_IS_A_TEST"), MD_IdentifierStyle_UpperCamelCase, MD_S8Lit(" "));
+            MD_String8 str = MD_S8Stylize(arena, MD_S8Lit("THIS_IS_A_TEST"),
+                                          MD_IdentifierStyle_UpperCamelCase, MD_S8Lit(" "));
             TestResult(MD_S8Match(str, MD_S8Lit("This Is A Test"), 0));
         }
         {
-            MD_String8 str = MD_S8Stylize(MD_S8Lit("this_is_a_test"), MD_IdentifierStyle_UpperCamelCase, MD_S8Lit(" "));
+            MD_String8 str = MD_S8Stylize(arena, MD_S8Lit("this_is_a_test"),
+                                          MD_IdentifierStyle_UpperCamelCase, MD_S8Lit(" "));
             TestResult(MD_S8Match(str, MD_S8Lit("This Is A Test"), 0));
         }
         {
-            MD_String8 str = MD_S8Stylize(MD_S8Lit("ThisIsATest"), MD_IdentifierStyle_UpperCamelCase, MD_S8Lit(" "));
+            MD_String8 str = MD_S8Stylize(arena, MD_S8Lit("ThisIsATest"),
+                                          MD_IdentifierStyle_UpperCamelCase, MD_S8Lit(" "));
             TestResult(MD_S8Match(str, MD_S8Lit("This Is A Test"), 0));
         }
         {
-            MD_String8 str = MD_S8Stylize(MD_S8Lit("Here is another test."), MD_IdentifierStyle_UpperCamelCase, MD_S8Lit(""));
+            MD_String8 str = MD_S8Stylize(arena, MD_S8Lit("Here is another test."),
+                                          MD_IdentifierStyle_UpperCamelCase, MD_S8Lit(""));
             TestResult(MD_S8Match(str, MD_S8Lit("HereIsAnotherTest."), 0));
         }
     }
@@ -437,7 +441,10 @@ int main(void)
     {
         TestResult(MD_S8Match(MD_StringFromNodeKind(MD_NodeKind_Main), MD_S8Lit("Main"), 0));
         TestResult(MD_S8Match(MD_StringFromNodeKind(MD_NodeKind_Main), MD_S8Lit("Main"), 0));
-        MD_String8List list = MD_StringListFromNodeFlags(MD_NodeFlag_StringLiteral | MD_NodeFlag_HasParenLeft | MD_NodeFlag_IsBeforeSemicolon);
+        MD_String8List list = MD_StringListFromNodeFlags(arena, 
+                                                         MD_NodeFlag_StringLiteral |
+                                                         MD_NodeFlag_HasParenLeft |
+                                                         MD_NodeFlag_IsBeforeSemicolon);
         MD_b32 match = 1;
         for(MD_String8Node *node = list.first; node; node = node->next)
         {