diff --git a/cachier/cores/memory.py b/cachier/cores/memory.py
index de87da00..f7fe83dc 100644
--- a/cachier/cores/memory.py
+++ b/cachier/cores/memory.py
@@ -4,7 +4,7 @@
 from datetime import datetime
 
 from .._types import HashFunc
-from .base import _BaseCore
+from .base import _BaseCore, _get_func_str
 
 
 class _MemoryCore(_BaseCore):
@@ -14,9 +14,12 @@ def __init__(self, hash_func: HashFunc, wait_for_calc_timeout: int):
         super().__init__(hash_func, wait_for_calc_timeout)
         self.cache = {}
 
+    def _hash_func_key(self, key):
+        return f"{_get_func_str(self.func)}:{key}"
+
     def get_entry_by_key(self, key, reload=False):
         with self.lock:
-            return key, self.cache.get(key, None)
+            return key, self.cache.get(self._hash_func_key(key), None)
 
     def set_entry(self, key, func_res):
         with self.lock:
@@ -24,10 +27,10 @@ def set_entry(self, key, func_res):
                 # we need to retain the existing condition so that
                 # mark_entry_not_calculated can notify all possibly-waiting
                 # threads about it
-                cond = self.cache[key]["condition"]
+                cond = self.cache[self._hash_func_key(key)]["condition"]
             except KeyError:  # pragma: no cover
                 cond = None
-            self.cache[key] = {
+            self.cache[self._hash_func_key(key)] = {
                 "value": func_res,
                 "time": datetime.now(),
                 "stale": False,
@@ -40,10 +43,10 @@ def mark_entry_being_calculated(self, key):
             condition = threading.Condition()
             # condition.acquire()
             try:
-                self.cache[key]["being_calculated"] = True
-                self.cache[key]["condition"] = condition
+                self.cache[self._hash_func_key(key)]["being_calculated"] = True
+                self.cache[self._hash_func_key(key)]["condition"] = condition
             except KeyError:
-                self.cache[key] = {
+                self.cache[self._hash_func_key(key)] = {
                     "value": None,
                     "time": datetime.now(),
                     "stale": False,
@@ -54,7 +57,7 @@ def mark_entry_being_calculated(self, key):
     def mark_entry_not_calculated(self, key):
         with self.lock:
             try:
-                entry = self.cache[key]
+                entry = self.cache[self._hash_func_key(key)]
             except KeyError:  # pragma: no cover
                 return  # that's ok, we don't need an entry in that case
             entry["being_calculated"] = False
@@ -67,13 +70,13 @@ def mark_entry_not_calculated(self, key):
 
     def wait_on_entry_calc(self, key):
         with self.lock:  # pragma: no cover
-            entry = self.cache[key]
+            entry = self.cache[self._hash_func_key(key)]
             if not entry["being_calculated"]:
                 return entry["value"]
         entry["condition"].acquire()
         entry["condition"].wait()
         entry["condition"].release()
-        return self.cache[key]["value"]
+        return self.cache[self._hash_func_key(key)]["value"]
 
     def clear_cache(self):
         with self.lock:
diff --git a/cachier/cores/pickle.py b/cachier/cores/pickle.py
index 9479b54a..9b4a9fd2 100644
--- a/cachier/cores/pickle.py
+++ b/cachier/cores/pickle.py
@@ -86,26 +86,18 @@ def __init__(
         self.separate_files = _update_with_defaults(
             separate_files, "separate_files"
         )
-        self._cache_fname = None
-        self._cache_fpath = None
 
     @property
     def cache_fname(self) -> str:
-        if self._cache_fname is None:
-            fname = f".{self.func.__module__}.{self.func.__qualname__}"
-            self._cache_fname = fname.replace("<", "_").replace(">", "_")
-        return self._cache_fname
+        fname = f".{self.func.__module__}.{self.func.__qualname__}"
+        return fname.replace("<", "_").replace(">", "_")
 
     @property
     def cache_fpath(self) -> str:
-        if self._cache_fpath is None:
-            os.makedirs(self.cache_dir, exist_ok=True)
-            self._cache_fpath = os.path.abspath(
-                os.path.join(
-                    os.path.realpath(self.cache_dir), self.cache_fname
-                )
-            )
-        return self._cache_fpath
+        os.makedirs(self.cache_dir, exist_ok=True)
+        return os.path.abspath(
+            os.path.join(os.path.realpath(self.cache_dir), self.cache_fname)
+        )
 
     def _reload_cache(self):
         with self.lock:
@@ -113,11 +105,8 @@ def _reload_cache(self):
                 with portalocker.Lock(
                     self.cache_fpath, mode="rb"
                 ) as cache_file:
-                    try:
-                        self.cache = pickle.load(cache_file)  # noqa: S301
-                    except EOFError:
-                        self.cache = {}
-            except FileNotFoundError:
+                    self.cache = pickle.load(cache_file)  # noqa: S301
+            except (FileNotFoundError, EOFError):
                 self.cache = {}
 
     def _get_cache(self):
@@ -180,11 +169,12 @@ def set_entry(self, key, func_res):
         }
         if self.separate_files:
             self._save_cache(key_data, key)
-        else:
-            with self.lock:
-                cache = self._get_cache()
-                cache[key] = key_data
-                self._save_cache(cache)
+            return  # pragma: no cover
+
+        with self.lock:
+            cache = self._get_cache()
+            cache[key] = key_data
+            self._save_cache(cache)
 
     def mark_entry_being_calculated_separate_files(self, key):
         self._save_cache(
@@ -205,19 +195,20 @@ def mark_entry_not_calculated_separate_files(self, key):
     def mark_entry_being_calculated(self, key):
         if self.separate_files:
             self.mark_entry_being_calculated_separate_files(key)
-        else:
-            with self.lock:
-                cache = self._get_cache()
-                try:
-                    cache[key]["being_calculated"] = True
-                except KeyError:
-                    cache[key] = {
-                        "value": None,
-                        "time": datetime.now(),
-                        "stale": False,
-                        "being_calculated": True,
-                    }
-                self._save_cache(cache)
+            return  # pragma: no cover
+
+        with self.lock:
+            cache = self._get_cache()
+            try:
+                cache[key]["being_calculated"] = True
+            except KeyError:
+                cache[key] = {
+                    "value": None,
+                    "time": datetime.now(),
+                    "stale": False,
+                    "being_calculated": True,
+                }
+            self._save_cache(cache)
 
     def mark_entry_not_calculated(self, key):
         if self.separate_files:
@@ -263,9 +254,10 @@ def clear_cache(self):
     def clear_being_calculated(self):
         if self.separate_files:
             self._clear_being_calculated_all_cache_files()
-        else:
-            with self.lock:
-                cache = self._get_cache()
-                for key in cache:
-                    cache[key]["being_calculated"] = False
-                self._save_cache(cache)
+            return  # pragma: no cover
+
+        with self.lock:
+            cache = self._get_cache()
+            for key in cache:
+                cache[key]["being_calculated"] = False
+            self._save_cache(cache)
diff --git a/tests/test_general.py b/tests/test_general.py
index 6eba04b0..c3a3621d 100644
--- a/tests/test_general.py
+++ b/tests/test_general.py
@@ -344,44 +344,89 @@ def dummy_func(a, b=2):
     assert count == 1
 
 
-def test_runtime_handling(tmpdir):
-    count = 0
+@pytest.mark.parametrize("backend", ["memory", "pickle"])
+def test_diff_functions_same_args(tmpdir, backend: str):
+    count_p = count_m = 0
+
+    @cachier.cachier(cache_dir=tmpdir, backend=backend)
+    def fn_plus(a, b=2):
+        nonlocal count_p
+        count_p += 1
+        return a + b
 
-    def dummy_func(a, b):
-        nonlocal count
-        count += 1
+    @cachier.cachier(cache_dir=tmpdir, backend=backend)
+    def fn_minus(a, b=2):
+        nonlocal count_m
+        count_m += 1
+        return a - b
+
+    assert count_p == count_m == 0
+
+    for fn, expected in [(fn_plus, 3), (fn_minus, -1)]:
+        assert fn(1) == expected
+        assert fn(a=1, b=2) == expected
+    assert count_p == 1
+    assert count_m == 1
+
+
+@pytest.mark.parametrize("backend", ["memory", "pickle"])
+def test_runtime_handling(tmpdir, backend):
+    count_p = count_m = 0
+
+    def fn_plus(a, b=2):
+        nonlocal count_p
+        count_p += 1
         return a + b
 
-    cachier_ = cachier.cachier(cache_dir=tmpdir)
-    assert count == 0
-    cachier_(dummy_func)(a=1, b=2)
-    cachier_(dummy_func)(a=1, b=2)
-    assert count == 1
+    def fn_minus(a, b=2):
+        nonlocal count_m
+        count_m += 1
+        return a - b
+
+    cachier_ = cachier.cachier(cache_dir=tmpdir, backend=backend)
+    assert count_p == count_m == 0
+
+    for fn, expected in [(fn_plus, 3), (fn_minus, -1)]:
+        assert cachier_(fn)(1, 2) == expected
+        assert cachier_(fn)(a=1, b=2) == expected
+    assert count_p == 1
+    assert count_m == 1
+
+    for fn, expected in [(fn_plus, 5), (fn_minus, 1)]:
+        assert cachier_(fn)(3, 2) == expected
+        assert cachier_(fn)(a=3, b=2) == expected
+    assert count_p == 2
+    assert count_m == 2
 
 
 def test_partial_handling(tmpdir):
-    count = 0
+    count_p = count_m = 0
 
-    def dummy_func(a, b=2):
-        nonlocal count
-        count += 1
+    def fn_plus(a, b=2):
+        nonlocal count_p
+        count_p += 1
         return a + b
 
-    cachier_ = cachier.cachier(cache_dir=tmpdir)
-    assert count == 0
+    def fn_minus(a, b=2):
+        nonlocal count_m
+        count_m += 1
+        return a - b
 
-    dummy_ = functools.partial(dummy_func, 1)
-    cachier_(dummy_)()
+    cachier_ = cachier.cachier(cache_dir=tmpdir)
+    assert count_p == count_m == 0
 
-    dummy_ = functools.partial(dummy_func, a=1)
-    cachier_(dummy_)()
+    for fn, expected in [(fn_plus, 3), (fn_minus, -1)]:
+        dummy_ = functools.partial(fn, 1)
+        assert cachier_(dummy_)() == expected
 
-    dummy_ = functools.partial(dummy_func, b=2)
-    cachier_(dummy_)(1)
+        dummy_ = functools.partial(fn, a=1)
+        assert cachier_(dummy_)() == expected
 
-    assert count == 1
+        dummy_ = functools.partial(fn, b=2)
+        assert cachier_(dummy_)(1) == expected
 
-    cachier_(dummy_func)(1, 2)
-    cachier_(dummy_func)(a=1, b=2)
+        assert cachier_(fn)(1, 2) == expected
+        assert cachier_(fn)(a=1, b=2) == expected
 
-    assert count == 1
+    assert count_p == 1
+    assert count_m == 1