diff --git a/py/builtinhelp.c b/py/builtinhelp.c
index 13735635e3..84d69caf35 100644
--- a/py/builtinhelp.c
+++ b/py/builtinhelp.c
@@ -67,10 +67,10 @@ STATIC void mp_help_add_from_map(mp_obj_t list, const mp_map_t *map) {
 #if MICROPY_MODULE_FROZEN
 STATIC void mp_help_add_from_names(mp_obj_t list, const char *name) {
     while (*name) {
-        size_t l = strlen(name);
+        size_t len = strlen(name);
         // name should end in '.py' and we strip it off
-        mp_obj_list_append(list, mp_obj_new_str(name, l - 3));
-        name += l + 1;
+        mp_obj_list_append(list, mp_obj_new_str(name, len - 3));
+        name += len + 1;
     }
 }
 #endif
@@ -80,14 +80,9 @@ STATIC void mp_help_print_modules(void) {
 
     mp_help_add_from_map(list, &mp_builtin_module_map);
 
-    #if MICROPY_MODULE_FROZEN_STR
-    extern const char mp_frozen_str_names[];
-    mp_help_add_from_names(list, mp_frozen_str_names);
-    #endif
-
-    #if MICROPY_MODULE_FROZEN_MPY
-    extern const char mp_frozen_mpy_names[];
-    mp_help_add_from_names(list, mp_frozen_mpy_names);
+    #if MICROPY_MODULE_FROZEN
+    extern const char mp_frozen_names[];
+    mp_help_add_from_names(list, mp_frozen_names);
     #endif
 
     // sort the list so it's printed in alphabetical order
diff --git a/py/builtinimport.c b/py/builtinimport.c
index 755ce779a7..3e336633d9 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -50,6 +50,9 @@
 // Must be a string of one byte.
 #define PATH_SEP_CHAR "/"
 
+// Virtual sys.path entry that maps to the frozen modules.
+#define MP_FROZEN_PATH_PREFIX ".frozen/"
+
 bool mp_obj_is_package(mp_obj_t module) {
     mp_obj_t dest[2];
     mp_load_method_maybe(module, MP_QSTR___path__, dest);
@@ -62,9 +65,10 @@ bool mp_obj_is_package(mp_obj_t module) {
 // will return whether the path is a file, directory, or doesn't exist.
 STATIC mp_import_stat_t stat_path_or_frozen(const char *path) {
     #if MICROPY_MODULE_FROZEN
-    mp_import_stat_t st = mp_frozen_stat(path);
-    if (st != MP_IMPORT_STAT_NO_EXIST) {
-        return st;
+    // Only try and load as a frozen module if it starts with .frozen/.
+    const int frozen_path_prefix_len = strlen(MP_FROZEN_PATH_PREFIX);
+    if (strncmp(path, MP_FROZEN_PATH_PREFIX, frozen_path_prefix_len) == 0) {
+        return mp_find_frozen_module(path + frozen_path_prefix_len, NULL, NULL);
     }
     #endif
     return mp_import_stat(path);
@@ -193,32 +197,36 @@ STATIC void do_execute_raw_code(mp_obj_t module_obj, mp_raw_code_t *raw_code, co
 
 STATIC void do_load(mp_obj_t module_obj, vstr_t *file) {
     #if MICROPY_MODULE_FROZEN || MICROPY_ENABLE_COMPILER || (MICROPY_PERSISTENT_CODE_LOAD && MICROPY_HAS_FILE_READER)
-    char *file_str = vstr_null_terminated_str(file);
+    const char *file_str = vstr_null_terminated_str(file);
     #endif
 
     // If we support frozen modules (either as str or mpy) then try to find the
     // requested filename in the list of frozen module filenames.
     #if MICROPY_MODULE_FROZEN
     void *modref;
-    int frozen_type = mp_find_frozen_module(file_str, file->len, &modref);
+    int frozen_type;
+    const int frozen_path_prefix_len = strlen(MP_FROZEN_PATH_PREFIX);
+    if (strncmp(file_str, MP_FROZEN_PATH_PREFIX, frozen_path_prefix_len) == 0) {
+        mp_find_frozen_module(file_str + frozen_path_prefix_len, &frozen_type, &modref);
 
-    // If we support frozen str modules and the compiler is enabled, and we
-    // found the filename in the list of frozen files, then load and execute it.
-    #if MICROPY_MODULE_FROZEN_STR
-    if (frozen_type == MP_FROZEN_STR) {
-        do_load_from_lexer(module_obj, modref);
-        return;
-    }
-    #endif
+        // If we support frozen str modules and the compiler is enabled, and we
+        // found the filename in the list of frozen files, then load and execute it.
+        #if MICROPY_MODULE_FROZEN_STR
+        if (frozen_type == MP_FROZEN_STR) {
+            do_load_from_lexer(module_obj, modref);
+            return;
+        }
+        #endif
 
-    // If we support frozen mpy modules and we found a corresponding file (and
-    // its data) in the list of frozen files, execute it.
-    #if MICROPY_MODULE_FROZEN_MPY
-    if (frozen_type == MP_FROZEN_MPY) {
-        do_execute_raw_code(module_obj, modref, file_str);
-        return;
+        // If we support frozen mpy modules and we found a corresponding file (and
+        // its data) in the list of frozen files, execute it.
+        #if MICROPY_MODULE_FROZEN_MPY
+        if (frozen_type == MP_FROZEN_MPY) {
+            do_execute_raw_code(module_obj, modref, file_str + frozen_path_prefix_len);
+            return;
+        }
+        #endif
     }
-    #endif
 
     #endif // MICROPY_MODULE_FROZEN
 
diff --git a/py/frozenmod.c b/py/frozenmod.c
index a250c02151..6cb68d1ec0 100644
--- a/py/frozenmod.c
+++ b/py/frozenmod.c
@@ -5,6 +5,7 @@
  *
  * Copyright (c) 2015 Paul Sokolovsky
  * Copyright (c) 2016 Damien P. George
+ * Copyright (c) 2021 Jim Mussared
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -31,6 +32,13 @@
 #include "py/lexer.h"
 #include "py/frozenmod.h"
 
+#if MICROPY_MODULE_FROZEN
+
+// Null-separated frozen file names. All string-type entries are listed first,
+// followed by mpy-type entries. Use mp_frozen_str_sizes to determine how
+// many string entries.
+extern const char mp_frozen_names[];
+
 #if MICROPY_MODULE_FROZEN_STR
 
 #ifndef MICROPY_MODULE_FROZEN_LEXER
@@ -39,118 +47,89 @@
 mp_lexer_t *MICROPY_MODULE_FROZEN_LEXER(qstr src_name, const char *str, mp_uint_t len, mp_uint_t free_len);
 #endif
 
-extern const char mp_frozen_str_names[];
+// Size in bytes of each string entry, followed by a zero (terminator).
 extern const uint32_t mp_frozen_str_sizes[];
+// Null-separated string content.
 extern const char mp_frozen_str_content[];
-
-// On input, *len contains size of name, on output - size of content
-const char *mp_find_frozen_str(const char *str, size_t *len) {
-    const char *name = mp_frozen_str_names;
-
-    size_t offset = 0;
-    for (int i = 0; *name != 0; i++) {
-        size_t l = strlen(name);
-        if (l == *len && !memcmp(str, name, l)) {
-            *len = mp_frozen_str_sizes[i];
-            return mp_frozen_str_content + offset;
-        }
-        name += l + 1;
-        offset += mp_frozen_str_sizes[i] + 1;
-    }
-    return NULL;
-}
-
-STATIC mp_lexer_t *mp_lexer_frozen_str(const char *str, size_t len) {
-    size_t name_len = len;
-    const char *content = mp_find_frozen_str(str, &len);
-
-    if (content == NULL) {
-        return NULL;
-    }
-
-    qstr source = qstr_from_strn(str, name_len);
-    mp_lexer_t *lex = MICROPY_MODULE_FROZEN_LEXER(source, content, len, 0);
-    return lex;
-}
-
-#endif
+#endif // MICROPY_MODULE_FROZEN_STR
 
 #if MICROPY_MODULE_FROZEN_MPY
 
 #include "py/emitglue.h"
 
-extern const char mp_frozen_mpy_names[];
 extern const mp_raw_code_t *const mp_frozen_mpy_content[];
 
-STATIC const mp_raw_code_t *mp_find_frozen_mpy(const char *str, size_t len) {
-    const char *name = mp_frozen_mpy_names;
-    for (size_t i = 0; *name != 0; i++) {
-        size_t l = strlen(name);
-        if (l == len && !memcmp(str, name, l)) {
-            return mp_frozen_mpy_content[i];
-        }
-        name += l + 1;
-    }
-    return NULL;
-}
+#endif // MICROPY_MODULE_FROZEN_MPY
 
-#endif
-
-#if MICROPY_MODULE_FROZEN
-
-STATIC mp_import_stat_t mp_frozen_stat_helper(const char *name, const char *str) {
+// Search for "str" as a frozen entry, returning the stat result
+// (no-exist/file/dir), as well as the type (none/str/mpy) and data.
+// frozen_type can be NULL if its value isn't needed (and then data is assumed to be NULL).
+mp_import_stat_t mp_find_frozen_module(const char *str, int *frozen_type, void **data) {
     size_t len = strlen(str);
+    const char *name = mp_frozen_names;
+
+    if (frozen_type != NULL) {
+        *frozen_type = MP_FROZEN_NONE;
+    }
+
+    // Count the number of str lengths we have to find how many str entries.
+    size_t num_str = 0;
+    #if MICROPY_MODULE_FROZEN_STR && MICROPY_MODULE_FROZEN_MPY
+    for (const uint32_t *s = mp_frozen_str_sizes; *s != 0; ++s) {
+        ++num_str;
+    }
+    #endif
+
+    for (size_t i = 0; *name != 0; i++) {
+        size_t entry_len = strlen(name);
+        if (entry_len >= len && memcmp(str, name, len) == 0) {
+            // Query is a prefix of the current entry.
+            if (entry_len == len) {
+                // Exact match --> file.
+
+                if (frozen_type != NULL) {
+                    #if MICROPY_MODULE_FROZEN_STR
+                    if (i < num_str) {
+                        *frozen_type = MP_FROZEN_STR;
+                        // Use the size table to figure out where this index starts.
+                        size_t offset = 0;
+                        for (size_t j = 0; j < i; ++j) {
+                            offset += mp_frozen_str_sizes[j] + 1;
+                        }
+                        size_t content_len = mp_frozen_str_sizes[i];
+                        const char *content = &mp_frozen_str_content[offset];
+
+                        // Note: str & len have been updated by find_frozen_entry to strip
+                        // the ".frozen/" prefix (to avoid this being a distinct qstr to
+                        // the original path QSTR in frozen_content.c).
+                        qstr source = qstr_from_strn(str, len);
+                        mp_lexer_t *lex = MICROPY_MODULE_FROZEN_LEXER(source, content, content_len, 0);
+                        *data = lex;
+                    }
+                    #endif
+
+                    #if MICROPY_MODULE_FROZEN_MPY
+                    if (i >= num_str) {
+                        *frozen_type = MP_FROZEN_MPY;
+                        // Load the corresponding index as a raw_code, taking
+                        // into account any string entries to offset by.
+                        *data = (void *)mp_frozen_mpy_content[i - num_str];
+                    }
+                    #endif
+                }
 
-    for (int i = 0; *name != 0; i++) {
-        size_t l = strlen(name);
-        if (l >= len && !memcmp(str, name, len)) {
-            if (name[len] == 0) {
                 return MP_IMPORT_STAT_FILE;
             } else if (name[len] == '/') {
+                // Matches up to directory separator, this is a valid
+                // directory path.
                 return MP_IMPORT_STAT_DIR;
             }
         }
-        name += l + 1;
+        // Skip null separator.
+        name += entry_len + 1;
     }
-    return MP_IMPORT_STAT_NO_EXIST;
-}
-
-mp_import_stat_t mp_frozen_stat(const char *str) {
-    mp_import_stat_t stat;
-
-    #if MICROPY_MODULE_FROZEN_STR
-    stat = mp_frozen_stat_helper(mp_frozen_str_names, str);
-    if (stat != MP_IMPORT_STAT_NO_EXIST) {
-        return stat;
-    }
-    #endif
-
-    #if MICROPY_MODULE_FROZEN_MPY
-    stat = mp_frozen_stat_helper(mp_frozen_mpy_names, str);
-    if (stat != MP_IMPORT_STAT_NO_EXIST) {
-        return stat;
-    }
-    #endif
 
     return MP_IMPORT_STAT_NO_EXIST;
 }
 
-int mp_find_frozen_module(const char *str, size_t len, void **data) {
-    #if MICROPY_MODULE_FROZEN_STR
-    mp_lexer_t *lex = mp_lexer_frozen_str(str, len);
-    if (lex != NULL) {
-        *data = lex;
-        return MP_FROZEN_STR;
-    }
-    #endif
-    #if MICROPY_MODULE_FROZEN_MPY
-    const mp_raw_code_t *rc = mp_find_frozen_mpy(str, len);
-    if (rc != NULL) {
-        *data = (void *)rc;
-        return MP_FROZEN_MPY;
-    }
-    #endif
-    return MP_FROZEN_NONE;
-}
-
-#endif
+#endif // MICROPY_MODULE_FROZEN
diff --git a/py/frozenmod.h b/py/frozenmod.h
index 8a477d028e..be735e85bd 100644
--- a/py/frozenmod.h
+++ b/py/frozenmod.h
@@ -35,8 +35,6 @@ enum {
     MP_FROZEN_MPY,
 };
 
-int mp_find_frozen_module(const char *str, size_t len, void **data);
-const char *mp_find_frozen_str(const char *str, size_t *len);
-mp_import_stat_t mp_frozen_stat(const char *str);
+mp_import_stat_t mp_find_frozen_module(const char *str, int *frozen_type, void **data);
 
 #endif // MICROPY_INCLUDED_PY_FROZENMOD_H
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index 5b4e0dc48e..405813941b 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -60,6 +60,10 @@ Q(<string>)
 Q(<stdin>)
 Q(utf-8)
 
+#if MICROPY_MODULE_FROZEN
+Q(.frozen)
+#endif
+
 #if MICROPY_ENABLE_PYSTACK
 Q(pystack exhausted)
 #endif
diff --git a/shared/runtime/pyexec.c b/shared/runtime/pyexec.c
index 006ec096f7..2dceb647c3 100644
--- a/shared/runtime/pyexec.c
+++ b/shared/runtime/pyexec.c
@@ -674,7 +674,7 @@ int pyexec_file(const char *filename) {
 
 int pyexec_file_if_exists(const char *filename) {
     #if MICROPY_MODULE_FROZEN
-    if (mp_frozen_stat(filename) == MP_IMPORT_STAT_FILE) {
+    if (mp_find_frozen_module(filename, NULL, NULL) == MP_IMPORT_STAT_FILE) {
         return pyexec_frozen_module(filename);
     }
     #endif
@@ -687,7 +687,8 @@ int pyexec_file_if_exists(const char *filename) {
 #if MICROPY_MODULE_FROZEN
 int pyexec_frozen_module(const char *name) {
     void *frozen_data;
-    int frozen_type = mp_find_frozen_module(name, strlen(name), &frozen_data);
+    int frozen_type;
+    mp_find_frozen_module(name, &frozen_type, &frozen_data);
 
     switch (frozen_type) {
         #if MICROPY_MODULE_FROZEN_STR
diff --git a/tools/makemanifest.py b/tools/makemanifest.py
index e37ae74cfd..8cdc3eb774 100644
--- a/tools/makemanifest.py
+++ b/tools/makemanifest.py
@@ -233,12 +233,17 @@ def freeze_internal(kind, path, script, opt):
         manifest_list.append((kind, path, script, opt))
 
 
+# Formerly make-frozen.py.
+# This generates:
+# - MP_FROZEN_STR_NAMES macro
+# - mp_frozen_str_sizes
+# - mp_frozen_str_content
 def generate_frozen_str_content(paths):
     def module_name(f):
         return f
 
     modules = []
-    output = []
+    output = [b"#include <stdint.h>\n"]
 
     for path in paths:
         root = path.rstrip("/")
@@ -250,21 +255,19 @@ def generate_frozen_str_content(paths):
                 st = os.stat(fullpath)
                 modules.append((path, fullpath[root_len + 1 :], st))
 
-    output.append("#include <stdint.h>\n")
-    output.append("const char mp_frozen_str_names[] = {\n")
+    output.append(b"#define MP_FROZEN_STR_NAMES \\\n")
     for _path, f, st in modules:
         m = module_name(f)
-        output.append('"%s\\0"\n' % m)
-    output.append('"\\0"};\n')
+        output.append(b'"%s\\0" \\\n' % m.encode())
+    output.append(b"\n")
 
-    output.append("const uint32_t mp_frozen_str_sizes[] = {\n")
+    output.append(b"const uint32_t mp_frozen_str_sizes[] = { ")
 
     for _path, f, st in modules:
-        output.append("%d," % st.st_size)
+        output.append(b"%d, " % st.st_size)
+    output.append(b"0 };\n")
 
-    output.append("0};\n")
-
-    output.append("const char mp_frozen_str_content[] = {\n")
+    output.append(b"const char mp_frozen_str_content[] = {\n")
     for path, f, st in modules:
         data = open(path + "/" + f, "rb").read()
 
@@ -276,8 +279,8 @@ def generate_frozen_str_content(paths):
         # to be able to read the resulting C code as ASCII when possible.
 
         data = bytearray(data)  # so Python2 extracts each byte as an integer
-        esc_dict = {ord("\n"): "\\n", ord("\r"): "\\r", ord('"'): '\\"', ord("\\"): "\\\\"}
-        output.append('"')
+        esc_dict = {ord("\n"): b"\\n", ord("\r"): b"\\r", ord('"'): b'\\"', ord("\\"): b"\\\\"}
+        output.append(b'"')
         break_str = False
         for c in data:
             try:
@@ -285,16 +288,16 @@ def generate_frozen_str_content(paths):
             except KeyError:
                 if 32 <= c <= 126:
                     if break_str:
-                        output.append('" "')
+                        output.append(b'" "')
                         break_str = False
-                    output.append(chr(c))
+                    output.append(chr(c).encode())
                 else:
-                    output.append("\\x%02x" % c)
+                    output.append(b"\\x%02x" % c)
                     break_str = True
-        output.append('\\0"\n')
+        output.append(b'\\0"\n')
 
-    output.append('"\\0"};\n')
-    return "".join(output)
+    output.append(b'"\\0"\n};\n\n')
+    return b"".join(output)
 
 
 def main():
@@ -414,8 +417,8 @@ def main():
             b"const qstr_pool_t mp_qstr_frozen_const_pool = {\n"
             b"    (qstr_pool_t*)&mp_qstr_const_pool, MP_QSTRnumber_of, 0, 0\n"
             b"};\n"
-            b'const char mp_frozen_mpy_names[1] = {"\\0"};\n'
-            b"const mp_raw_code_t *const mp_frozen_mpy_content[1] = {NULL};\n"
+            b'const char mp_frozen_names[] = { MP_FROZEN_STR_NAMES "\\0"};\n'
+            b"const mp_raw_code_t *const mp_frozen_mpy_content[] = {NULL};\n"
         )
 
     # Generate output
@@ -423,7 +426,7 @@ def main():
     mkdir(args.output)
     with open(args.output, "wb") as f:
         f.write(b"//\n// Content for MICROPY_MODULE_FROZEN_STR\n//\n")
-        f.write(output_str.encode())
+        f.write(output_str)
         f.write(b"//\n// Content for MICROPY_MODULE_FROZEN_MPY\n//\n")
         f.write(output_mpy)
 
diff --git a/tools/mpy-tool.py b/tools/mpy-tool.py
index 6868ed5d4e..aa0272111c 100755
--- a/tools/mpy-tool.py
+++ b/tools/mpy-tool.py
@@ -886,7 +886,11 @@ def freeze_mpy(base_qstrs, raw_codes):
         rc.freeze(rc.source_file.str.replace("/", "_")[:-3] + "_")
 
     print()
-    print("const char mp_frozen_mpy_names[] = {")
+    print("const char mp_frozen_names[] = {")
+    print("#ifdef MP_FROZEN_STR_NAMES")
+    # makemanifest.py might also include some frozen string content.
+    print("MP_FROZEN_STR_NAMES")
+    print("#endif")
     for rc in raw_codes:
         module_name = rc.source_file.str
         print('"%s\\0"' % module_name)