diff --git a/vm/io.c b/vm/io.c
index 55787e1ab1..0e54336085 100644
--- a/vm/io.c
+++ b/vm/io.c
@@ -35,8 +35,8 @@ void primitive_fopen(void)
 	char *path, *mode;
 	FILE* file;
 	maybe_gc(0);
-	mode = pop_char_string();
-	path = pop_char_string();
+	mode = unbox_char_string();
+	path = unbox_char_string();
 	file = fopen(path,mode);
 	if(file == NULL)
 		io_error();
diff --git a/vm/os-unix.c b/vm/os-unix.c
index d87204e702..d4faec93ed 100644
--- a/vm/os-unix.c
+++ b/vm/os-unix.c
@@ -131,7 +131,7 @@ void primitive_cwd(void)
 void primitive_cd(void)
 {
 	maybe_gc(0);
-	chdir(pop_char_string());
+	chdir(unbox_char_string());
 }
 
 BOUNDED_BLOCK *alloc_bounded_block(CELL size)
diff --git a/vm/os-windows.c b/vm/os-windows.c
index c5202f679c..80c9b3195b 100644
--- a/vm/os-windows.c
+++ b/vm/os-windows.c
@@ -163,7 +163,7 @@ void primitive_cwd(void)
 void primitive_cd(void)
 {
 	maybe_gc(0);
-	SetCurrentDirectory(pop_char_string());
+	SetCurrentDirectory(unbox_char_string());
 }
 
 BOUNDED_BLOCK *alloc_bounded_block(CELL size)
diff --git a/vm/run.c b/vm/run.c
index 8365502dd1..8aeeb349fa 100644
--- a/vm/run.c
+++ b/vm/run.c
@@ -170,7 +170,7 @@ void primitive_os_env(void)
 
 	maybe_gc(0);
 
-	name = pop_char_string();
+	name = unbox_char_string();
 	value = getenv(name);
 	if(value == NULL)
 		dpush(F);
diff --git a/vm/types.c b/vm/types.c
index 89c8963079..a3766ab912 100644
--- a/vm/types.c
+++ b/vm/types.c
@@ -356,16 +356,9 @@ F_ARRAY *allot_c_string(CELL capacity, CELL size)
 		else \
 			return (type*)(string_to_##type##_alien(s,check) + 1); \
 	} \
-	type *pop_##type##_string(void) \
-	{ \
-		return to_##type##_string(untag_string(dpop()),true); \
-	} \
 	type *unbox_##type##_string(void) \
 	{ \
-		if(type_of(dpeek()) == STRING_TYPE) \
-			return pop_##type##_string(); \
-		else \
-			return unbox_alien(); \
+		return to_##type##_string(untag_string(dpop()),true); \
 	} \
 	void primitive_string_to_##type##_alien(void) \
 	{ \
diff --git a/vm/types.h b/vm/types.h
index 00211e611d..6be2d9cbd1 100644
--- a/vm/types.h
+++ b/vm/types.h
@@ -110,7 +110,6 @@ void char_string_to_memory(F_STRING *s, char *string);
 void primitive_char_string_to_memory(void);
 F_ARRAY *string_to_char_alien(F_STRING *s, bool check);
 char* to_char_string(F_STRING *s, bool check);
-char *pop_char_string(void);
 DLLEXPORT char *unbox_char_string(void);
 void primitive_string_to_char_alien(void);
 
@@ -118,7 +117,6 @@ void u16_string_to_memory(F_STRING *s, u16 *string);
 void primitive_u16_string_to_memory(void);
 F_ARRAY *string_to_u16_alien(F_STRING *s, bool check);
 u16* to_u16_string(F_STRING *s, bool check);
-u16 *pop_u16_string(void);
 DLLEXPORT u16 *unbox_u16_string(void);
 void primitive_string_to_u16_alien(void);