diff --git a/src/stc/stc.cpp b/src/stc/stc.cpp
index f1cfe240df..c9b08e945c 100644
--- a/src/stc/stc.cpp
+++ b/src/stc/stc.cpp
@@ -4509,7 +4509,7 @@ bool wxStyledTextCtrl::GetUseAntiAliasing() {
 }
 
 void wxStyledTextCtrl::AnnotationClearLine(int line) {
-    SendMsg(SCI_ANNOTATIONSETTEXT, line, NULL);
+    SendMsg(SCI_ANNOTATIONSETTEXT, line, (sptr_t)NULL);
 }
 
 
diff --git a/src/stc/stc.cpp.in b/src/stc/stc.cpp.in
index eec517db9f..d9036a438b 100644
--- a/src/stc/stc.cpp.in
+++ b/src/stc/stc.cpp.in
@@ -647,7 +647,7 @@ bool wxStyledTextCtrl::GetUseAntiAliasing() {
 }
 
 void wxStyledTextCtrl::AnnotationClearLine(int line) {
-    SendMsg(SCI_ANNOTATIONSETTEXT, line, NULL);
+    SendMsg(SCI_ANNOTATIONSETTEXT, line, (sptr_t)NULL);
 }