diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/StandardConfigDataLocationResolver.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/StandardConfigDataLocationResolver.java
index f21970c391..c6ca85e671 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/StandardConfigDataLocationResolver.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/StandardConfigDataLocationResolver.java
@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.io.File;
 
 import org.apache.commons.logging.Log;
 
@@ -212,7 +213,7 @@ public class StandardConfigDataLocationResolver
 			}
 		}
 		throw new IllegalStateException("File extension is not known to any PropertySourceLoader. "
-				+ "If the location is meant to reference a directory, it must end in '/'");
+				+ "If the location is meant to reference a directory, it must end in '/' or File.separator");
 	}
 
 	private String getLoadableFileExtension(PropertySourceLoader loader, String file) {
@@ -225,7 +226,7 @@ public class StandardConfigDataLocationResolver
 	}
 
 	private boolean isDirectory(String resourceLocation) {
-		return resourceLocation.endsWith("/");
+		return resourceLocation.endsWith("/") || resourceLocation.endsWith(File.separator);
 	}
 
 	private List<StandardConfigDataResource> resolve(Set<StandardConfigDataReference> references) {