diff --git a/src/cc65/assignment.c b/src/cc65/assignment.c
index c67ac1ce5..207e01588 100644
--- a/src/cc65/assignment.c
+++ b/src/cc65/assignment.c
@@ -127,7 +127,13 @@ void Assignment (ExprDesc* Expr)
 
     /* We must have an lvalue for an assignment */
     if (ED_IsRVal (Expr)) {
-        Error ("Invalid lvalue in assignment");
+        if (IsTypeArray (Expr->Type)) {
+            Error ("Array type '%s' is not assignable", GetFullTypeName (Expr->Type));
+        } else if (IsTypeFunc (Expr->Type)) {
+            Error ("Function type '%s' is not assignable", GetFullTypeName (Expr->Type));
+        } else {
+            Error ("Assignment to rvalue");
+        }
     }
 
     /* Check for assignment to const */
diff --git a/src/cc65/datatype.c b/src/cc65/datatype.c
index 005e6109b..aaee7260f 100644
--- a/src/cc65/datatype.c
+++ b/src/cc65/datatype.c
@@ -903,7 +903,7 @@ unsigned CheckedSizeOf (const Type* T)
 {
     unsigned Size = SizeOf (T);
     if (Size == 0) {
-        Error ("Size of data type is unknown");
+        Error ("Size of type '%s' is unknown", GetFullTypeName (T));
         Size = SIZEOF_CHAR;     /* Don't return zero */
     }
     return Size;
@@ -919,7 +919,7 @@ unsigned CheckedPSizeOf (const Type* T)
 {
     unsigned Size = PSizeOf (T);
     if (Size == 0) {
-        Error ("Size of data type is unknown");
+        Error ("Size of type '%s' is unknown", GetFullTypeName (T));
         Size = SIZEOF_CHAR;     /* Don't return zero */
     }
     return Size;
diff --git a/src/cc65/expr.c b/src/cc65/expr.c
index a99f17b55..8cd332173 100644
--- a/src/cc65/expr.c
+++ b/src/cc65/expr.c
@@ -1218,7 +1218,7 @@ static void StructRef (ExprDesc* Expr)
     NextToken ();
     const SymEntry Field = FindStructField (Expr->Type, Ident);
     if (Field.Type == 0) {
-        Error ("No field named '%s' found in %s", Ident, GetBasicTypeName (Expr->Type));
+        Error ("No field named '%s' found in '%s'", Ident, GetFullTypeName (Expr->Type));
         /* Make the expression an integer at address zero */
         ED_MakeConstAbs (Expr, 0, type_int);
         return;
@@ -1296,7 +1296,7 @@ static void StructRef (ExprDesc* Expr)
                 Flags = CF_LONG | CF_UNSIGNED | CF_CONST;
                 break;
             default:
-                Internal ("Invalid %s size: %u", GetBasicTypeName (Expr->Type), StructSize);
+                Internal ("Invalid '%s' size: %u", GetFullTypeName (Expr->Type), StructSize);
                 break;
         }
 
diff --git a/src/cc65/function.c b/src/cc65/function.c
index e6a974f98..5d0b09380 100644
--- a/src/cc65/function.c
+++ b/src/cc65/function.c
@@ -513,7 +513,7 @@ void NewFunc (SymEntry* Func)
             ** We don't currently support this case.
             */
             if (RType == Param->Type) {
-                Error ("Passing %s of this size by value is not supported", GetBasicTypeName (Param->Type));
+                Error ("Passing '%s' of this size by value is not supported", GetFullTypeName (Param->Type));
             }
         }
 
diff --git a/src/cc65/stmt.c b/src/cc65/stmt.c
index 27665e619..036cc2d89 100644
--- a/src/cc65/stmt.c
+++ b/src/cc65/stmt.c
@@ -333,7 +333,7 @@ static void ReturnStatement (void)
                 /* Handle struct/union specially */
                 ReturnType = GetStructReplacementType (Expr.Type);
                 if (ReturnType == Expr.Type) {
-                    Error ("Returning %s of this size by value is not supported", GetBasicTypeName (Expr.Type));
+                    Error ("Returning '%s' of this size by value is not supported", GetFullTypeName (Expr.Type));
                 }
                 LoadExpr (TypeOf (ReturnType), &Expr);