diff --git a/env.c b/env.c
index f78e3f3..4425b1e 100644
--- a/env.c
+++ b/env.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include "lake.h"
 #include "env.h"
 #include "hashtab.h"
diff --git a/lake.c b/lake.c
index b3447a8..18025b4 100644
--- a/lake.c
+++ b/lake.c
@@ -16,6 +16,7 @@
 #include "env.h"
 #include "lake.h"
 #include "parse.h"
+#include "string.h"
 
 static LakeVal _NIL = { TYPE_NIL, sizeof(LakeVal) };
 LakeVal *NIL = &_NIL;
diff --git a/string.c b/string.c
index c191791..b9f4817 100644
--- a/string.c
+++ b/string.c
@@ -18,6 +18,20 @@ void str_free(LakeStr *str)
     free(str);
 }
 
+NILP str_set(LakeStr *str, char *s)
+{
+    str->n = strlen(s);
+    str->s = strdup(s);
+    return NIL;
+}
+
+LakeStr *str_from_c(char *s)
+{
+    LakeStr *str = str_alloc();
+    str_set(str, s);
+    return str;
+}
+
 LakeStr *str_make(void)
 {
     return str_from_c("");
@@ -33,25 +47,11 @@ LakeStr *str_copy(LakeStr *str)
     return str_from_c(str->s);
 }
 
-LakeStr *str_from_c(char *s)
-{
-    LakeStr *str = str_alloc();
-    str_set(str, s);
-    return str;
-}
-
 char *str_val(LakeStr *str)
 {
     return strdup(str->s);
 }
 
-NILP str_set(LakeStr *str, char *s)
-{
-    str->n = strlen(s);
-    str->s = strdup(s);
-    return NIL;
-}
-
 #define MIN(a, b) (a < b ? a : b)
 
 LakeInt *str_cmp(LakeStr *a, LakeStr *b)