diff --git a/src/if_py_both.h b/src/if_py_both.h
index 3ab1851..0031003 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -2530,8 +2530,10 @@
 #if PY_MAJOR_VERSION >= 3
     else if (PyBytes_Check(obj))
     {
-	char_u	*result = (char_u *) PyBytes_AsString(obj);
+	char_u	*result;
 
+	if (PyString_AsStringAndSize(obj, (char **) &result, NULL) == -1)
+	    return -1;
 	if (result == NULL)
 	    return -1;
 
@@ -2549,7 +2551,8 @@
 	if (bytes == NULL)
 	    return -1;
 
-	result = (char_u *) PyBytes_AsString(bytes);
+	if(PyString_AsStringAndSize(bytes, (char **) &result, NULL) == -1)
+	    return -1;
 	if (result == NULL)
 	    return -1;
 
@@ -2572,7 +2575,8 @@
 	if (bytes == NULL)
 	    return -1;
 
-	result=(char_u *) PyString_AsString(bytes);
+	if(PyString_AsStringAndSize(bytes, (char **) &result, NULL) == -1)
+	    return -1;
 	if (result == NULL)
 	    return -1;
 
@@ -2587,8 +2591,10 @@
     }
     else if (PyString_Check(obj))
     {
-	char_u	*result = (char_u *) PyString_AsString(obj);
+	char_u	*result;
 
+	if(PyString_AsStringAndSize(obj, (char **) &result, NULL) == -1)
+	    return -1;
 	if (result == NULL)
 	    return -1;
 
diff --git a/src/if_python3.c b/src/if_python3.c
index 36ae8eb..0c10f8d 100644
--- a/src/if_python3.c
+++ b/src/if_python3.c
@@ -85,6 +85,7 @@
 #define PyString_AsString(obj) PyBytes_AsString(obj)
 #define PyString_Size(obj) PyBytes_GET_SIZE(bytes)
 #define PyString_FromString(repr) PyUnicode_FromString(repr)
+#define PyString_AsStringAndSize(obj, buffer, len) PyBytes_AsStringAndSize(obj, buffer, len)
 
 #if defined(DYNAMIC_PYTHON3) || defined(PROTO)
 
@@ -552,7 +553,7 @@
 #define DICTKEY_GET(err) \
     if (PyBytes_Check(keyObject)) \
     { \
-	if (PyBytes_AsStringAndSize(keyObject, (char **) &key, NULL) == -1) \
+	if (PyString_AsStringAndSize(keyObject, (char **) &key, NULL) == -1) \
 	    return err; \
     } \
     else if (PyUnicode_Check(keyObject)) \
@@ -560,7 +561,7 @@
 	bytes = PyString_AsBytes(keyObject); \
 	if (bytes == NULL) \
 	    return err; \
-	if (PyBytes_AsStringAndSize(bytes, (char **) &key, NULL) == -1) \
+	if (PyString_AsStringAndSize(bytes, (char **) &key, NULL) == -1) \
 	    return err; \
     } \
     else \
diff --git a/src/version.c b/src/version.c
index 3e0ac40..62bc819 100644
--- a/src/version.c
+++ b/src/version.c
@@ -720,6 +720,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    658,
+/**/
     657,
 /**/
     656,