diff --git a/cachito/workers/pkg_managers/ruby.py b/cachito/workers/pkg_managers/ruby.py
index 86ffa7298..4ff8a1e8e 100644
--- a/cachito/workers/pkg_managers/ruby.py
+++ b/cachito/workers/pkg_managers/ruby.py
@@ -1,3 +1,4 @@
+import re
 from dataclasses import dataclass
 from pathlib import Path
 
@@ -5,6 +6,9 @@
 
 from cachito.errors import ValidationError
 
+GIT_REF_FORMAT = re.compile(r"^[a-fA-F0-9]{40}$")
+PLATFORMS_RUBY = re.compile(r"^PLATFORMS\n {2}ruby\n\n", re.MULTILINE)
+
 
 @dataclass
 class GemMetadata:
@@ -22,19 +26,35 @@ def parse_gemlock(gemlock_path: Path):
     :param Path gemlock_path: the full path to Gemfile.lock
     :return: list of Gems
     """
-    all_gems = gemlock_parser.GemfileLockParser(str(gemlock_path)).all_gems
-    dependencies = []
+    if not gemlock_path.is_file():
+        return []
 
+    _validate_gemlock_platforms(gemlock_path)
+
+    dependencies = []
+    all_gems = gemlock_parser.GemfileLockParser(str(gemlock_path)).all_gems
     for gem in all_gems.values():
-        validate_gem_metadata(gem, gemlock_path.parent)
+        _validate_gem_metadata(gem, gemlock_path.parent)
         dependencies.append(GemMetadata(gem.name, gem.version, gem.type, gem.remote))
 
     return dependencies
 
 
-def validate_gem_metadata(gem, gemlock_dir):
+def _validate_gemlock_platforms(gemlock_path):
+    """Make sure Gemfile.lock contains only one platform - ruby."""
+    with open(gemlock_path) as f:
+        contents = f.read()
+
+    if not PLATFORMS_RUBY.search(contents):
+        msg = "PLATFORMS section of Gemfile.lock has to contain one and only platform - ruby."
+        raise ValidationError(msg)
+
+
+def _validate_gem_metadata(gem, gemlock_dir):
     """Validate parsed Gem.
 
+    While individual gems may contain platform information, this function doesn't check it,
+    because it expects the Gemfile.lock to be ruby platform specific.
     :param Gem gem: gem with information parsed from Gemfile.lock
     :param Path gemlock_dir: the root directory containing Gemfile.lock
     :raise: ValidationError
@@ -50,6 +70,12 @@ def validate_gem_metadata(gem, gemlock_dir):
     elif gem.type == "GIT":
         if not gem.remote.startswith("https://"):
             raise ValidationError("All Ruby GIT dependencies have to use HTTPS protocol.")
+        if not GIT_REF_FORMAT.match(gem.version):
+            msg = (
+                f"No git ref for gem: {gem.name} (expected 40 hexadecimal characters, "
+                f"got: {gem.version})."
+            )
+            raise ValidationError(msg)
     elif gem.type == "PATH":
         dependency_dir = gemlock_dir / gem.remote
         if not dependency_dir.exists():
diff --git a/tests/test_workers/test_pkg_managers/test_ruby.py b/tests/test_workers/test_pkg_managers/test_ruby.py
index 123ea85a6..f406ade92 100644
--- a/tests/test_workers/test_pkg_managers/test_ruby.py
+++ b/tests/test_workers/test_pkg_managers/test_ruby.py
@@ -14,7 +14,7 @@ class TestGemlockParsing:
             # GEM dependency
             (
                 dedent(
-                    """\
+                    """
                     GEM
                       remote: https://rubygems.org/
                       specs:
@@ -47,6 +47,9 @@ class TestGemlockParsing:
                         ci_reporter (2.0.0)
                           builder (>= 2.1.2)
 
+                    PLATFORMS
+                      ruby
+
                     DEPENDENCIES
                       ci_reporter_shell!
                     """
@@ -108,6 +111,20 @@ def test_parsing_of_valid_path_dependency(self, tmpdir):
     @pytest.mark.parametrize(
         "file_contents, expected_error",
         (
+            (
+                dedent(
+                    """
+                    GEM
+                      remote: https://rubygems.org/
+                      specs:
+                        zeitwerk (2.5.4)
+
+                    DEPENDENCIES
+                      zeitwerk
+                    """
+                ),
+                "PLATFORMS section of Gemfile.lock has to contain one and only platform - ruby.",
+            ),
             (
                 dedent(
                     """
@@ -116,6 +133,9 @@ def test_parsing_of_valid_path_dependency(self, tmpdir):
                       specs:
                         zeitwerk (2.5.4)
 
+                    PLATFORMS
+                      ruby
+
                     DEPENDENCIES
                       zeitwerk
                     """
@@ -133,11 +153,33 @@ def test_parsing_of_valid_path_dependency(self, tmpdir):
                         json-schema (3.0.0)
                           addressable (>= 2.4)
 
+                    PLATFORMS
+                      ruby
+
                     DEPENDENCIES
                       json-schema!
                     """
                 ),
-                "Ruby GIT dependencies have to use HTTPS protocol.",
+                "All Ruby GIT dependencies have to use HTTPS protocol.",
+            ),
+            (
+                dedent(
+                    """
+                    GIT
+                      remote: https://github.com/3scale/json-schema.git
+                      revision: xxx
+                      specs:
+                        json-schema (3.0.0)
+                          addressable (>= 2.4)
+
+                    PLATFORMS
+                      ruby
+
+                    DEPENDENCIES
+                      json-schema!
+                    """
+                ),
+                "No git ref for gem: json-schema (expected 40 hexadecimal characters, got: xxx).",
             ),
             (
                 dedent(
@@ -148,6 +190,9 @@ def test_parsing_of_valid_path_dependency(self, tmpdir):
                         active-docs (1.0.0)
                           railties (> 3.1)
 
+                    PLATFORMS
+                      ruby
+
                     DEPENDENCIES
                       active-docs!
                     """
@@ -163,6 +208,9 @@ def test_parsing_of_valid_path_dependency(self, tmpdir):
                         active-docs (1.0.0)
                           railties (> 3.1)
 
+                    PLATFORMS
+                      ruby
+
                     DEPENDENCIES
                       active-docs!
                     """
@@ -177,11 +225,32 @@ def test_parsing_of_valid_path_dependency(self, tmpdir):
                       specs:
                         zeitwerk
 
+                    PLATFORMS
+                      ruby
+
+                    DEPENDENCIES
+                      zeitwerk
+                    """
+                ),
+                "Unspecified name or version of a RubyGem.",
+            ),
+            (
+                dedent(
+                    """
+                    GEM
+                      remote: https://rubygems.org/
+                      specs:
+                        zeitwerk (2.5.4)
+
+                    PLATFORMS
+                      ruby
+                      x86_64-linux
+
                     DEPENDENCIES
                       zeitwerk
                     """
                 ),
-                "Unspecified name or version",
+                "PLATFORMS section of Gemfile.lock has to contain one and only platform - ruby.",
             ),
         ),
     )
@@ -190,5 +259,7 @@ def test_parsing_of_invalid_cases(self, file_contents, expected_error, tmpdir):
         gemfile_lock = tmpdir.join("Gemfile.lock")
         gemfile_lock.write(file_contents)
 
-        with pytest.raises(ValidationError, match=expected_error):
+        with pytest.raises(ValidationError) as exc_info:
             parse_gemlock(Path(gemfile_lock))
+
+        assert str(exc_info.value) == expected_error