diff --git a/src/xkbcomp/scanner.c b/src/xkbcomp/scanner.c
index 8bff375..7db9a7f 100644
--- a/src/xkbcomp/scanner.c
+++ b/src/xkbcomp/scanner.c
@@ -200,9 +200,18 @@ XkbParseString(struct xkb_context *ctx, const char *string, size_t len,
     struct scanner scanner;
     scanner_init(&scanner, ctx, string, len, file_name, NULL);
 
-    /* Skip UTF-8 encoded BOM (U+FEFF) */
-    /* See: https://www.unicode.org/faq/utf_bom.html#bom5 */
-    scanner_str(&scanner, "\xef\xbb\xbf", 3);
+    /* Basic detection of wrong character encoding.
+       The first character relevant to the grammar must be ASCII:
+       whitespace, section, comment */
+    if (!scanner_check_supported_char_encoding(&scanner)) {
+        scanner_err(&scanner,
+            "This could be a file encoding issue. "
+            "Supported encodings must be backward compatible with ASCII.");
+        scanner_err(&scanner,
+            "E.g. ISO/CEI 8859 and UTF-8 are supported "
+            "but UTF-16, UTF-32 and CP1026 are not.");
+        return NULL;
+    }
 
     return parse(ctx, &scanner, map);
 }
diff --git a/test/buffercomp.c b/test/buffercomp.c
index b9b5e9d..091a876 100644
--- a/test/buffercomp.c
+++ b/test/buffercomp.c
@@ -31,6 +31,59 @@
 
 #define DATA_PATH "keymaps/stringcomp.data"
 
+static bool
+test_encodings(struct xkb_context *ctx)
+{
+    struct xkb_keymap *keymap;
+
+    /* Accept UTF-8 encoded BOM (U+FEFF) */
+    const char utf8_with_bom[] =
+        "\xef\xbb\xbfxkb_keymap {"
+        "  xkb_keycodes { include \"evdev\" };"
+        "  xkb_types { include \"complete\" };"
+        "  xkb_compat { include \"complete\" };"
+        "  xkb_symbols { include \"pc\" };"
+        "};";
+    keymap = test_compile_buffer(ctx, utf8_with_bom, sizeof(utf8_with_bom));
+    assert(keymap);
+    xkb_keymap_unref(keymap);
+
+    /* Reject UTF-16LE encoded string */
+    const char utf16_le[] =
+        "x\0k\0b\0_\0k\0e\0y\0m\0a\0p\0 \0{\0\n\0"
+        " \0 \0x\0k\0b\0_\0k\0e\0y\0c\0o\0d\0e\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0e\0v\0d\0e\0v\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0t\0y\0p\0e\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0c\0o\0m\0p\0l\0e\0t\0e\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0c\0o\0m\0p\0a\0t\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0c\0o\0m\0p\0l\0e\0t\0e\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0s\0y\0m\0b\0o\0l\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0p\0c\0\"\0 \0}\0;\0\n\0"
+        "}\0;\0";
+    keymap = test_compile_buffer(ctx, utf16_le, sizeof(utf16_le));
+    assert(!keymap);
+
+    /* Reject UTF-16LE with BOM encoded string */
+    const char utf16_le_with_bom[] =
+        "\xff\xfex\0k\0b\0_\0k\0e\0y\0m\0a\0p\0 \0{\0\n\0"
+        " \0 \0x\0k\0b\0_\0k\0e\0y\0c\0o\0d\0e\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0e\0v\0d\0e\0v\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0t\0y\0p\0e\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0c\0o\0m\0p\0l\0e\0t\0e\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0c\0o\0m\0p\0a\0t\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0c\0o\0m\0p\0l\0e\0t\0e\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0s\0y\0m\0b\0o\0l\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0p\0c\0\"\0 \0}\0;\0\n\0"
+        "}\0;\0";
+    keymap = test_compile_buffer(ctx, utf16_le_with_bom, sizeof(utf16_le_with_bom));
+    assert(!keymap);
+
+    /* Reject UTF-16BE encoded string */
+    const char utf16_be[] =
+        "\0x\0k\0b\0_\0k\0e\0y\0m\0a\0p\0 \0{\0\n\0"
+        " \0 \0x\0k\0b\0_\0k\0e\0y\0c\0o\0d\0e\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0e\0v\0d\0e\0v\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0t\0y\0p\0e\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0c\0o\0m\0p\0l\0e\0t\0e\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0c\0o\0m\0p\0a\0t\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0c\0o\0m\0p\0l\0e\0t\0e\0\"\0 \0}\0;\0\n\0"
+        " \0 \0x\0k\0b\0_\0s\0y\0m\0b\0o\0l\0s\0 \0{\0 \0i\0n\0c\0l\0u\0d\0e\0 \0\"\0p\0c\0\"\0 \0}\0;\0\n\0"
+        "}\0;";
+    keymap = test_compile_buffer(ctx, utf16_be, sizeof(utf16_be));
+    assert(!keymap);
+
+    return true;
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -78,17 +131,7 @@ main(int argc, char *argv[])
     keymap = test_compile_buffer(ctx, "", 0);
     assert(!keymap);
 
-    /* Accept UTF-8 encoded BOM (U+FEFF) */
-    const char *bom =
-        "\xef\xbb\xbfxkb_keymap {"
-        "  xkb_keycodes { include \"evdev\" };"
-        "  xkb_types { include \"complete\" };"
-        "  xkb_compat { include \"complete\" };"
-        "  xkb_symbols { include \"pc\" };"
-        "};";
-    keymap = test_compile_buffer(ctx, bom, strlen(bom));
-    assert(keymap);
-    xkb_keymap_unref(keymap);
+    assert(test_encodings(ctx));
 
     /* Make sure we can recompile our output for a normal keymap from rules. */
     keymap = test_compile_rules(ctx, NULL, NULL,