diff --git a/pyo3-build-config/src/import_lib.rs b/pyo3-build-config/src/import_lib.rs
index 6d4e2ee47df..0925a861b5b 100644
--- a/pyo3-build-config/src/import_lib.rs
+++ b/pyo3-build-config/src/import_lib.rs
@@ -7,7 +7,7 @@ use python3_dll_a::ImportLibraryGenerator;
 use target_lexicon::{Architecture, OperatingSystem, Triple};
 
 use super::{PythonImplementation, PythonVersion};
-use crate::errors::{Context, Result};
+use crate::errors::{Context, Error, Result};
 
 /// Generates the `python3.dll` or `pythonXY.dll` import library for Windows targets.
 ///
@@ -42,7 +42,9 @@ pub(super) fn generate_import_lib(
     let implementation = match py_impl {
         PythonImplementation::CPython => python3_dll_a::PythonImplementation::CPython,
         PythonImplementation::PyPy => python3_dll_a::PythonImplementation::PyPy,
-        PythonImplementation::GraalPy => python3_dll_a::PythonImplementation::GraalPy,
+        PythonImplementation::GraalPy => {
+            return Err(Error::from("No support for GraalPy on Windows"))
+        }
     };
 
     ImportLibraryGenerator::new(&arch, &env)