diff --git a/engine/compiler.c b/engine/compiler.c
index 79a1359..16fc02f 100644
--- a/engine/compiler.c
+++ b/engine/compiler.c
@@ -3904,8 +3904,10 @@ static sxi32 PH7_CompileClassInterface(ph7_gen_state *pGen) {
 		/* Extract the current keyword */
 		nKwrd = SX_PTR_TO_INT(pGen->pIn->pUserData);
 		if(nKwrd == PH7_KEYWORD_PRIVATE || nKwrd == PH7_KEYWORD_PROTECTED) {
-			/* Emit a warning and switch to public visibility */
-			PH7_GenCompileError(&(*pGen), E_WARNING, pGen->pIn->nLine, "interface: Access type must be public");
+			/* Preserve constant visibility recovery; non-public methods are fatal. */
+			PH7_GenCompileError(&(*pGen),
+							pGen->pIn + 1 < pGen->pEnd && SX_PTR_TO_INT(pGen->pIn[1].pUserData) == PH7_KEYWORD_CONST ? E_WARNING : E_ERROR,
+							pGen->pIn->nLine, "interface: Access type must be public");
 			nKwrd = PH7_KEYWORD_PUBLIC;
 		}
 		if(nKwrd == PH7_KEYWORD_PUBLIC) {