diff --git a/OMCompiler/Compiler/NBackEnd/Modules/3_Post/NBTearing.mo b/OMCompiler/Compiler/NBackEnd/Modules/3_Post/NBTearing.mo
index f5fe9307a6..dbb4428420 100644
--- a/OMCompiler/Compiler/NBackEnd/Modules/3_Post/NBTearing.mo
+++ b/OMCompiler/Compiler/NBackEnd/Modules/3_Post/NBTearing.mo
@@ -357,6 +357,7 @@ protected
     Tearing strict;
     list<Pointer<Variable>> vars_lst, cont_vars, disc_vars;
     list<Pointer<Equation>> eqns_lst, cont_eqns, disc_eqns;
+    Integer num_vars, num_eqns;
     list<Slice<EquationPointer>> residual_lst;
     Adjacency.Matrix adj;
     Matching matching;
@@ -370,14 +371,17 @@ protected
         eqns_lst := list(Slice.getT(eqn) for eqn in strict.residual_eqns);
         (cont_vars, disc_vars)  := List.splitOnTrue(vars_lst, function BVariable.isContinuous(init = systemType == NBSystem.SystemType.INI));
         (cont_eqns, disc_eqns)  := List.splitOnTrue(eqns_lst, Equation.isContinuous);
+        num_vars := sum(BVariable.size(var) for var in disc_vars);
+        num_eqns := sum(Equation.size(eqn) for eqn in disc_eqns);
 
-        if listLength(disc_vars) <> listLength(disc_eqns) then
+        if num_vars <> num_eqns then
           Error.addMessage(Error.INTERNAL_ERROR,{getInstanceName()
-            + " failed.\n" + StringUtil.headline_4("(" + intString(listLength(disc_vars)) + "|"
-            + intString(sum(BVariable.size(var) for var in disc_vars)) + ") Discrete Variables")
+            + " failed because number of discrete variables " + intString(num_vars) + " differs from number of discrete equations: " + intString(num_eqns)
+            + ".\n" + StringUtil.headline_4("(" + intString(listLength(disc_vars)) + "|"
+            + intString(num_vars) + ") Discrete Variables")
             + List.toString(disc_vars, BVariable.pointerToString, "", "\t", "\n\t", "\n", true) + "\n"
             + StringUtil.headline_4("(" + intString(listLength(disc_eqns)) + "|"
-            + intString(sum(Equation.size(eqn) for eqn in disc_eqns)) + ") Discrete Equations")
+            + intString(num_eqns) + ") Discrete Equations")
             + List.toString(disc_eqns, function Equation.pointerToString(str=""), "", "\t", "\n\t", "\n", true) + "\n"});
           fail();
         end if;