diff --git a/src/cc65/expr.c b/src/cc65/expr.c
index 7b9fd0b9d..817234ec8 100644
--- a/src/cc65/expr.c
+++ b/src/cc65/expr.c
@@ -3408,7 +3408,7 @@ static void opeq (const GenDesc* Gen, ExprDesc* Expr, const char* Op)
 
     /* There must be an integer or pointer on the left side */
     if (!IsClassInt (Expr->Type) && !IsTypePtr (Expr->Type)) {
-        Error ("Invalid left operand type");
+        Error ("Invalid left operand for binary operator '%s'", Op);
         /* Continue. Wrong code will be generated, but the compiler won't
         ** break, so this is the best error recovery.
         */
@@ -3532,7 +3532,7 @@ static void addsubeq (const GenDesc* Gen, ExprDesc *Expr, const char* Op)
 
     /* There must be an integer or pointer on the left side */
     if (!IsClassInt (Expr->Type) && !IsTypePtr (Expr->Type)) {
-        Error ("Invalid left operand type");
+        Error ("Invalid left operand for binary operator '%s'", Op);
         /* Continue. Wrong code will be generated, but the compiler won't
         ** break, so this is the best error recovery.
         */