diff --git a/sdks/go/pkg/beam/core/runtime/exec/sdf.go b/sdks/go/pkg/beam/core/runtime/exec/sdf.go
index be4f491b04cf..273f1dc21b05 100644
--- a/sdks/go/pkg/beam/core/runtime/exec/sdf.go
+++ b/sdks/go/pkg/beam/core/runtime/exec/sdf.go
@@ -175,22 +175,25 @@ func (n *SplitAndSizeRestrictions) StartBundle(ctx context.Context, id string, d
 //
 // Output Diagram:
 //
-//	  *FullValue {
-//	    Elm: *FullValue {
-//	      Elm:  *FullValue (original input)
-//	      Elm2: *FullValue {
-//			   Elm: Restriction
-//	        Elm2: Watermark estimator state
-//			 }
+//	*FullValue {
+//	  Elm: *FullValue {
+//	    Elm:  *FullValue (original input)
+//	    Elm2: *FullValue {
+//	      Elm: Restriction
+//	      Elm2: Watermark estimator state
 //	    }
-//	    Elm2: float64 (size)
-//	    Windows
-//	    Timestamps
 //	  }
+//	  Elm2: float64 (size)
+//	  Windows
+//	  Timestamps
+//	}
 func (n *SplitAndSizeRestrictions) ProcessElement(ctx context.Context, elm *FullValue, values ...ReStream) error {
 	rest := elm.Elm2.(*FullValue).Elm
 	ws := elm.Elm2.(*FullValue).Elm2
-	mainElm := elm.Elm.(*FullValue)
+
+	// If receiving directly from a datasource,
+	// the element may not be wrapped in a *FullValue
+	mainElm := convertIfNeeded(elm.Elm, &FullValue{})
 
 	splitRests := n.splitInv.Invoke(mainElm, rest)