diff --git a/src/disk.c b/src/disk.c
index 3f1cb227..3a15a973 100644
--- a/src/disk.c
+++ b/src/disk.c
@@ -90,22 +90,6 @@ static void _init_disk6(void) {
     }
 }
 
-static inline void cut_gz(char *name) {
-    size_t len = strlen(name);
-    if (len <= _GZLEN) {
-        return;
-    }
-    *(name+len-_GZLEN) = '\0';
-}
-
-static inline bool is_gz(const char * const name) {
-    size_t len = strlen(name);
-    if (len <= _GZLEN) {
-        return false;
-    }
-    return strncmp(name+len-_GZLEN, DISK_EXT_GZ, _GZLEN) == 0;
-}
-
 static inline bool is_nib(const char * const name) {
     size_t len = strlen(name);
     if (len <= _NIBLEN) {
@@ -1081,7 +1065,7 @@ bool disk6_loadState(StateHelper_s *helper) {
                     break;
                 }
 
-                snprintf(namebuf+namelen, gzlen, "%s", DISK_EXT_GZ);
+                snprintf(namebuf+namelen, gzlen, "%s", EXT_GZ);
                 namebuf[namelen+gzlen] = '\0';
                 LOG("LOAD disk[%lu] : (%u) %s", i, namelen, namebuf);
                 disk6_insert(i, namebuf, disk6.disk[i].is_protected);
diff --git a/src/disk.h b/src/disk.h
index 2d4b616e..5f040fb3 100644
--- a/src/disk.h
+++ b/src/disk.h
@@ -47,8 +47,6 @@
 #define _POLEN (sizeof(DISK_EXT_PO)-1)
 #define DISK_EXT_NIB ".nib"
 #define _NIBLEN (sizeof(DISK_EXT_NIB)-1)
-#define DISK_EXT_GZ  ".gz"
-#define _GZLEN (sizeof(DISK_EXT_GZ)-1)
 
 typedef struct diskette_t {
     char *file_name;
diff --git a/src/interface.c b/src/interface.c
index 91dc3e33..e8a8d5d7 100644
--- a/src/interface.c
+++ b/src/interface.c
@@ -222,28 +222,7 @@ void c_interface_print_submenu_centered( char *submenu, const int message_cols,
 
 /* ------------------------------------------------------------------------- */
 
-static int c_interface_cut_name(char *name)
-{
-    char *p = name + strlen(name) - 1;
-    int is_gz = 0;
-
-    if (p >= name && *p == 'z')
-    {
-        p--;
-        if (p >= name && *p == 'g')
-        {
-            p--;
-            if (p >= name && *p == '.')
-            {
-                *p-- = '\0';
-                is_gz = 1;
-            }
-        }
-    }
-
-    return is_gz;
-}
-
+#warning TODO FIXME : file selection and extension management should be made generic (merge similar code from disk.[hc] and possible Mac/iOS target) ...
 static int disk_select(const struct dirent *e) {
     char cmp[PATH_MAX] = { 0 };
 
@@ -469,8 +448,9 @@ void c_interface_select_diskette( int drive )
                                  namelist[ ent_no ]->d_name );
                     }
 
-                    if (c_interface_cut_name(temp))
+                    if (is_gz(temp))
                     {
+                        cut_gz(temp);
                         strncat(temp, " <gz>", PATH_MAX-1);
                     }
                     /* write protected disk in drive? */
diff --git a/src/interface.h b/src/interface.h
index f5f414f5..634805e4 100644
--- a/src/interface.h
+++ b/src/interface.h
@@ -89,5 +89,26 @@ extern void (*interface_setTouchMenuEnabled)(bool enabled);
 extern void (*interface_setTouchMenuVisibility)(float alpha);
 #endif
 
+#define EXT_GZ  ".gz"
+#define _GZLEN (sizeof(EXT_GZ)-1)
+
+// ----------------------------------------------------------------------------
+// file extension handling
+
+static inline bool is_gz(const char * const name) {
+    size_t len = strlen(name);
+    if (len <= _GZLEN) {
+        return false;
+    }
+    return strncmp(name+len-_GZLEN, EXT_GZ, _GZLEN) == 0;
+}
+
+static inline void cut_gz(char *name) {
+    size_t len = strlen(name);
+    if (len <= _GZLEN) {
+        return;
+    }
+    *(name+len-_GZLEN) = '\0';
+}
 
 #endif
diff --git a/src/zlib-helpers.c b/src/zlib-helpers.c
index 6f71b408..12692ba6 100644
--- a/src/zlib-helpers.c
+++ b/src/zlib-helpers.c
@@ -76,7 +76,7 @@ const char *zlib_deflate(const char* const src, const int expected_bytecount) {
             break;
         }
 
-        snprintf(dst, PATH_MAX-1, "%s%s", src, ".gz");
+        snprintf(dst, PATH_MAX-1, "%s%s", src, EXT_GZ);
 
         gzdest = gzopen(dst, "wb");
         if (gzdest == NULL) {
@@ -167,8 +167,8 @@ const char *zlib_inflate(const char* const src, const int expected_bytecount) {
 
         size_t len = strlen(src);
         snprintf(dst, PATH_MAX-1, "%s", src);
-        if (! ( (dst[len-3] == '.') && (dst[len-2] == 'g') && (dst[len-1] == 'z') ) ) {
-            ERRLOG("Expected filename ending in .gz");
+        if (!is_gz(dst)) {
+            ERRLOG("Expected filename ending in %s", EXT_GZ);
             break;
         }
         dst[len-3] = '\0';