diff --git a/optimade/__init__.py b/optimade/__init__.py
index 12e76002e..69a2a54e9 100644
--- a/optimade/__init__.py
+++ b/optimade/__init__.py
@@ -1,2 +1,19 @@
 __version__ = "0.16.12"
 __api_version__ = "1.1.0"
+
+import sys
+
+if sys.version_info.minor == 7:
+    import warnings
+
+    warnings.filterwarnings(
+        action="once",
+        message=r"v0\.17 of the `optimade` package.*",
+        category=DeprecationWarning,
+        append=False,
+    )
+    warnings.warn(
+        "v0.17 of the `optimade` package will be the last to support Python 3.7. "
+        "Please upgrade to Python 3.8+ to use v0.18 and later versions of `optimade`.",
+        DeprecationWarning,
+    )