diff --git a/spring-test/src/main/java/org/springframework/test/context/support/TestPropertySourceUtils.java b/spring-test/src/main/java/org/springframework/test/context/support/TestPropertySourceUtils.java
index ff19e4bbc8..7531b93082 100644
--- a/spring-test/src/main/java/org/springframework/test/context/support/TestPropertySourceUtils.java
+++ b/spring-test/src/main/java/org/springframework/test/context/support/TestPropertySourceUtils.java
@@ -284,7 +284,7 @@ public abstract class TestPropertySourceUtils {
 			catch (Exception ex) {
 				throw new IllegalStateException("Failed to load test environment property from [" + pair + "]", ex);
 			}
-			Assert.state(props.size() == 1, "Failed to load exactly one test environment property from [" + pair + "]");
+			Assert.state(props.size() == 1, () -> "Failed to load exactly one test environment property from [" + pair + "]");
 			for (String name : props.stringPropertyNames()) {
 				map.put(name, props.getProperty(name));
 			}