diff --git a/docs/metadesk_reference.mdesk b/docs/metadesk_reference.mdesk
index 962443e..3e925b1 100644
--- a/docs/metadesk_reference.mdesk
+++ b/docs/metadesk_reference.mdesk
@@ -1086,6 +1086,7 @@ main:
 
 @send(Strings)
 @func MD_S8FromS16: {
+    arena: *MD_Arena,
     str: MD_String16,
     return: MD_String8,
 };
diff --git a/source/md.c b/source/md.c
index 8848c54..20cd227 100644
--- a/source/md.c
+++ b/source/md.c
@@ -859,7 +859,7 @@ MD_S8Stylize(MD_Arena *arena, MD_String8 string, MD_IdentifierStyle word_style,
     {
         result.size += separator.size*(words.node_count-1);
     }
-    result.str = MD_PushArray(MD_u8, result.size);
+    result.str = MD_PushArrayAr(arena, MD_u8, result.size);
     
     {
         MD_u64 write_pos = 0;
@@ -1081,11 +1081,13 @@ MD_Utf16FromCodepoint(MD_u16 *out, MD_u32 codepoint)
     return(advance);
 }
 
+// TODO(allen): arena "put back" operation to optimize these a bit more
+
 MD_FUNCTION MD_String8
-MD_S8FromS16(MD_String16 in)
+MD_S8FromS16(MD_Arena *arena, MD_String16 in)
 {
     MD_u64 cap = in.size*3;
-    MD_u8 *str = MD_PushArray(MD_u8, cap + 1);
+    MD_u8 *str = MD_PushArrayAr(arena, MD_u8, cap + 1);
     MD_u16 *ptr = in.str;
     MD_u16 *opl = ptr + in.size;
     MD_u64 size = 0;
@@ -1101,10 +1103,10 @@ MD_S8FromS16(MD_String16 in)
 }
 
 MD_FUNCTION MD_String16
-MD_S16FromS8(MD_String8 in)
+MD_S16FromS8(MD_Arena *arena, MD_String8 in)
 {
     MD_u64 cap = in.size*2;
-    MD_u16 *str = MD_PushArray(MD_u16, (cap + 1));
+    MD_u16 *str = MD_PushArrayAr(arena, MD_u16, (cap + 1));
     MD_u8 *ptr = in.str;
     MD_u8 *opl = ptr + in.size;
     MD_u64 size = 0;
@@ -1121,10 +1123,10 @@ MD_S16FromS8(MD_String8 in)
 }
 
 MD_FUNCTION MD_String8
-MD_S8FromS32(MD_String32 in)
+MD_S8FromS32(MD_Arena *arena, MD_String32 in)
 {
     MD_u64 cap = in.size*4;
-    MD_u8 *str = MD_PushArray(MD_u8, cap + 1);
+    MD_u8 *str = MD_PushArrayAr(arena, MD_u8, cap + 1);
     MD_u32 *ptr = in.str;
     MD_u32 *opl = ptr + in.size;
     MD_u64 size = 0;
@@ -1138,10 +1140,10 @@ MD_S8FromS32(MD_String32 in)
 }
 
 MD_FUNCTION MD_String32
-MD_S32FromS8(MD_String8 in)
+MD_S32FromS8(MD_Arena *arena, MD_String8 in)
 {
     MD_u64 cap = in.size;
-    MD_u32 *str = MD_PushArray(MD_u32, (cap + 1));
+    MD_u32 *str = MD_PushArrayAr(arena, MD_u32, (cap + 1));
     MD_u8 *ptr = in.str;
     MD_u8 *opl = ptr + in.size;
     MD_u64 size = 0;
diff --git a/source/md.h b/source/md.h
index df190f5..756ac2c 100644
--- a/source/md.h
+++ b/source/md.h
@@ -778,10 +778,10 @@ MD_FUNCTION MD_DecodedCodepoint MD_DecodeCodepointFromUtf8(MD_u8 *str, MD_u64 ma
 MD_FUNCTION MD_DecodedCodepoint MD_DecodeCodepointFromUtf16(MD_u16 *str, MD_u64 max);
 MD_FUNCTION MD_u32         MD_Utf8FromCodepoint(MD_u8 *out, MD_u32 codepoint);
 MD_FUNCTION MD_u32         MD_Utf16FromCodepoint(MD_u16 *out, MD_u32 codepoint);
-MD_FUNCTION MD_String8     MD_S8FromS16(MD_String16 str);
-MD_FUNCTION MD_String16    MD_S16FromS8(MD_String8 str);
-MD_FUNCTION MD_String8     MD_S8FromS32(MD_String32 str);
-MD_FUNCTION MD_String32    MD_S32FromS8(MD_String8 str);
+MD_FUNCTION MD_String8     MD_S8FromS16(MD_Arena *arena, MD_String16 str);
+MD_FUNCTION MD_String16    MD_S16FromS8(MD_Arena *arena, MD_String8 str);
+MD_FUNCTION MD_String8     MD_S8FromS32(MD_Arena *arena, MD_String32 str);
+MD_FUNCTION MD_String32    MD_S32FromS8(MD_Arena *arena, MD_String8 str);
 
 //~ File Name Strings
 
diff --git a/tests/unicode_test.c b/tests/unicode_test.c
index b504737..36fb310 100644
--- a/tests/unicode_test.c
+++ b/tests/unicode_test.c
@@ -1,19 +1,23 @@
 #include "md.h"
 #include "md.c"
 
+static MD_Arena *arena = 0;
+
 void run_test_on_string(MD_String8 string)
 {
-    MD_String16 s16 = MD_S16FromS8(string);
-    MD_String8  s8_ts16 = MD_S8FromS16(s16);
+    MD_String16 s16 = MD_S16FromS8(arena, string);
+    MD_String8  s8_ts16 = MD_S8FromS16(arena, s16);
     MD_Assert(MD_S8Match(s8_ts16, string, 0));
     
-    MD_String32 s32 = MD_S32FromS8(string);
-    MD_String8  s8_ts32 = MD_S8FromS32(s32);
+    MD_String32 s32 = MD_S32FromS8(arena, string);
+    MD_String8  s8_ts32 = MD_S8FromS32(arena, s32);
     MD_Assert(MD_S8Match(s8_ts32, string, 0));
 }
 
 int main(void)
 {
+    arena = MD_ArenaNew(1ull << 40);
+    
     // TODO(allen): throw more at this.
     
     char test_string_c[] = "Foo bar; test the unicode\n\t\0Etc";