diff --git a/eeschema/sch_screen.h b/eeschema/sch_screen.h
index d010544fec..36dba2cf19 100644
--- a/eeschema/sch_screen.h
+++ b/eeschema/sch_screen.h
@@ -530,11 +530,6 @@ private:
 
     void clearLibSymbols();
 
-    /**
-     * Migrate the symbol's V6 simulation model SCH_FIELDs to their V7 equivalents
-     */
-    void migrateSimModel( SCH_SYMBOL& aSymbol );
-
 public:
     /**
      * last value for the zoom level, useful in Eeschema when changing the current displayed
diff --git a/eeschema/sim/sim_model.cpp b/eeschema/sim/sim_model.cpp
index d80e4498ee..342b0f77da 100644
--- a/eeschema/sim/sim_model.cpp
+++ b/eeschema/sim/sim_model.cpp
@@ -1650,6 +1650,9 @@ void SIM_MODEL::MigrateSimModel( T_symbol& aSymbol, const PROJECT* aProject )
                             {
                                 model->SetParamValue( ii, tokenizer.GetNextToken().ToStdString(),
                                                       SIM_VALUE_GRAMMAR::NOTATION::SPICE );
+
+                                if( !model->GetParam( ii ).value->HasValue() )
+                                    THROW_IO_ERROR( "fall back to raw SPICE" );
                             }
 
                             spiceTypeInfo.m_Text = SIM_MODEL::TypeInfo( type ).fieldValue;