diff --git a/src/main/java/software/amazon/smithy/lsp/ext/FileCachingCollector.java b/src/main/java/software/amazon/smithy/lsp/ext/FileCachingCollector.java
index ec9c8ef5..334bcd28 100644
--- a/src/main/java/software/amazon/smithy/lsp/ext/FileCachingCollector.java
+++ b/src/main/java/software/amazon/smithy/lsp/ext/FileCachingCollector.java
@@ -240,7 +240,10 @@ private Optional<OperationShape> getOperationForInlinedInputOrOutput(Shape shape
             String suffix = getOperationInputOrOutputSuffix(shape, preamble);
             String shapeName = shape.getId().getName();
 
-            String matchingOperationName = shapeName.substring(0, shapeName.length() - suffix.length());
+            String matchingOperationName =
+                shapeName.endsWith(suffix)
+                    ? shapeName.substring(0, shapeName.length() - suffix.length())
+                    : shapeName;
             ShapeId matchingOperationId = ShapeId.fromParts(shape.getId().getNamespace(), matchingOperationName);
 
             return model.shapes(OperationShape.class)