diff --git a/OMCompiler/Compiler/NFFrontEnd/NFAttributes.mo b/OMCompiler/Compiler/NFFrontEnd/NFAttributes.mo
index 74f792e0aa..ac74592d54 100644
--- a/OMCompiler/Compiler/NFFrontEnd/NFAttributes.mo
+++ b/OMCompiler/Compiler/NFFrontEnd/NFAttributes.mo
@@ -106,6 +106,19 @@ public
       Replaceable.NOT_REPLACEABLE()
     );
 
+  constant Attributes AUGMENTED_ATTR =
+    ATTRIBUTES(
+      ConnectorType.AUGMENTED,
+      Parallelism.NON_PARALLEL,
+      Variability.CONTINUOUS,
+      Direction.NONE,
+      InnerOuter.NOT_INNER_OUTER,
+      false,
+      false,
+      Replaceable.NOT_REPLACEABLE()
+    );
+
+
   record ATTRIBUTES
     ConnectorType.Type connectorType;
     Parallelism parallelism;
diff --git a/OMCompiler/Compiler/NFFrontEnd/NFConnections.mo b/OMCompiler/Compiler/NFFrontEnd/NFConnections.mo
index 987b05674a..ca82cfff66 100644
--- a/OMCompiler/Compiler/NFFrontEnd/NFConnections.mo
+++ b/OMCompiler/Compiler/NFFrontEnd/NFConnections.mo
@@ -140,15 +140,25 @@ public
   protected
     Component comp;
     Connector c;
+    DAE.ElementSource src;
   algorithm
     // Collect all flow variables.
     for var in flatModel.variables loop
       comp := InstNode.component(ComponentRef.node(var.name));
 
       if Component.isFlow(comp) then
-        c := Connector.fromFacedCref(var.name, var.ty,
-          NFConnector.Face.INSIDE, ElementSource.createElementSource(Component.info(comp)));
+        // Add all flow variables as inside connectors, to generate default
+        // equations if they're not connected.
+        src := ElementSource.createElementSource(Component.info(comp));
+        c := Connector.fromFacedCref(var.name, var.ty, NFConnector.Face.INSIDE, src);
         conns := addFlow(c, conns);
+
+        // Also add outside connectors for flow variables that were added during
+        // augmentation of expandable connectors.
+        if ConnectorType.isAugmented(var.attributes.connectorType) then
+          c := Connector.fromFacedCref(var.name, var.ty, NFConnector.Face.OUTSIDE, src);
+          conns := addFlow(c, conns);
+        end if;
       end if;
     end for;
   end collectFlows;
diff --git a/OMCompiler/Compiler/NFFrontEnd/NFExpandableConnectors.mo b/OMCompiler/Compiler/NFFrontEnd/NFExpandableConnectors.mo
index 35dd8fa93e..96427bd278 100644
--- a/OMCompiler/Compiler/NFFrontEnd/NFExpandableConnectors.mo
+++ b/OMCompiler/Compiler/NFFrontEnd/NFExpandableConnectors.mo
@@ -443,7 +443,7 @@ algorithm
     end for;
   else
     var := Variable.VARIABLE(connectorName, connectorType, NFBinding.EMPTY_BINDING,
-      Visibility.PUBLIC, NFAttributes.DEFAULT_ATTR, {}, {},
+      Visibility.PUBLIC, NFAttributes.AUGMENTED_ATTR, {}, {},
       SOME(SCode.COMMENT(NONE(), SOME("virtual variable in expandable connector"))),
       info, NFBackendExtension.DUMMY_BACKEND_INFO);
     vars := var :: vars;
diff --git a/OMCompiler/Compiler/NFFrontEnd/NFPrefixes.mo b/OMCompiler/Compiler/NFFrontEnd/NFPrefixes.mo
index 6922e7c974..a133f28785 100644
--- a/OMCompiler/Compiler/NFFrontEnd/NFPrefixes.mo
+++ b/OMCompiler/Compiler/NFFrontEnd/NFPrefixes.mo
@@ -46,6 +46,7 @@ package ConnectorType
   constant Type VIRTUAL             = intBitLShift(1, 4) "A virtual connector used in a connection.";
   constant Type CONNECTOR           = intBitLShift(1, 5) "A non-expandable connector that contains elements.";
   constant Type EXPANDABLE          = intBitLShift(1, 6) "An expandable connector.";
+  constant Type AUGMENTED           = intBitLShift(1, 7) "A variable added during augmentation of an expandable connector.";
 
   // flow/stream
   constant Type FLOW_STREAM_MASK = intBitOr(FLOW, STREAM);
@@ -217,6 +218,14 @@ package ConnectorType
     annotation(__OpenModelica_EarlyInline = true);
   end setPresent;
 
+  function isAugmented
+    input Type cty;
+    output Boolean augmented;
+  algorithm
+    augmented := intBitAnd(cty, AUGMENTED) > 0;
+    annotation(__OpenModelica_EarlyInline = true);
+  end isAugmented;
+
   function toString
     input Type cty;
     output String str;
diff --git a/testsuite/flattening/modelica/scodeinst/ExpandableConnector13.mo b/testsuite/flattening/modelica/scodeinst/ExpandableConnector13.mo
new file mode 100644
index 0000000000..74bfc01dc8
--- /dev/null
+++ b/testsuite/flattening/modelica/scodeinst/ExpandableConnector13.mo
@@ -0,0 +1,119 @@
+// name: ExpandableConnector13
+// keywords: expandable connector
+// status: correct
+// cflags: -d=newInst
+//
+// Checks that potentially present non-connector variables in an expandable
+// connector doesn't generate warnings about unbalanced connectors.
+//
+
+connector Pin
+  Real v;
+  flow Real i;
+end Pin;
+
+model Ground
+  Pin p;
+equation
+  p.v = 0;
+end Ground;
+
+expandable connector C
+end C;
+
+model ModelA
+  C c;
+  Ground ground1;
+  Ground ground2;
+  Ground ground3;
+equation
+  connect(ground1.p, c.p1);
+  connect(ground2.p, c.p2);
+  connect(ground3.p, c.p3);
+end ModelA;
+
+model ModelB
+  C c;
+  Ground ground1;
+equation
+  connect(ground1.p, c.p1);
+end ModelB;
+
+model ExpandableConnector13
+  ModelA m1;
+  ModelA m2;
+  ModelB m3;
+equation
+  connect(m1.c, m2.c);
+  connect(m1.c, m3.c);
+end ExpandableConnector13;
+
+// Result:
+// class ExpandableConnector13
+//   Real m1.c.p1.i "virtual variable in expandable connector";
+//   Real m1.c.p1.v "virtual variable in expandable connector";
+//   Real m1.c.p2.i "virtual variable in expandable connector";
+//   Real m1.c.p2.v "virtual variable in expandable connector";
+//   Real m1.c.p3.i "virtual variable in expandable connector";
+//   Real m1.c.p3.v "virtual variable in expandable connector";
+//   Real m2.c.p1.i "virtual variable in expandable connector";
+//   Real m2.c.p1.v "virtual variable in expandable connector";
+//   Real m2.c.p2.i "virtual variable in expandable connector";
+//   Real m2.c.p2.v "virtual variable in expandable connector";
+//   Real m2.c.p3.i "virtual variable in expandable connector";
+//   Real m2.c.p3.v "virtual variable in expandable connector";
+//   Real m3.c.p1.i "virtual variable in expandable connector";
+//   Real m3.c.p1.v "virtual variable in expandable connector";
+//   Real m3.c.p2.i "virtual variable in expandable connector";
+//   Real m3.c.p2.v "virtual variable in expandable connector";
+//   Real m3.c.p3.i "virtual variable in expandable connector";
+//   Real m3.c.p3.v "virtual variable in expandable connector";
+//   Real m1.ground1.p.v;
+//   Real m1.ground1.p.i;
+//   Real m1.ground2.p.v;
+//   Real m1.ground2.p.i;
+//   Real m1.ground3.p.v;
+//   Real m1.ground3.p.i;
+//   Real m2.ground1.p.v;
+//   Real m2.ground1.p.i;
+//   Real m2.ground2.p.v;
+//   Real m2.ground2.p.i;
+//   Real m2.ground3.p.v;
+//   Real m2.ground3.p.i;
+//   Real m3.ground1.p.v;
+//   Real m3.ground1.p.i;
+// equation
+//   m1.ground1.p.v = m1.c.p1.v;
+//   m1.ground2.p.v = m1.c.p2.v;
+//   m1.ground3.p.v = m1.c.p3.v;
+//   m2.ground1.p.v = m2.c.p1.v;
+//   m2.ground2.p.v = m2.c.p2.v;
+//   m2.ground3.p.v = m2.c.p3.v;
+//   m3.ground1.p.v = m3.c.p1.v;
+//   m1.c.p1.v = m3.c.p1.v;
+//   m1.c.p1.v = m2.c.p1.v;
+//   m1.c.p2.v = m3.c.p2.v;
+//   m1.c.p2.v = m2.c.p2.v;
+//   m1.c.p3.v = m3.c.p3.v;
+//   m1.c.p3.v = m2.c.p3.v;
+//   m3.c.p1.i + m2.c.p1.i + m1.c.p1.i = 0.0;
+//   m3.c.p2.i + m2.c.p2.i + m1.c.p2.i = 0.0;
+//   m3.c.p3.i + m2.c.p3.i + m1.c.p3.i = 0.0;
+//   m3.c.p2.i = 0.0;
+//   m3.c.p3.i = 0.0;
+//   m1.ground1.p.i - m1.c.p1.i = 0.0;
+//   m1.ground2.p.i - m1.c.p2.i = 0.0;
+//   m1.ground3.p.i - m1.c.p3.i = 0.0;
+//   m2.ground1.p.i - m2.c.p1.i = 0.0;
+//   m2.ground2.p.i - m2.c.p2.i = 0.0;
+//   m2.ground3.p.i - m2.c.p3.i = 0.0;
+//   m3.ground1.p.i - m3.c.p1.i = 0.0;
+//   m1.ground1.p.v = 0.0;
+//   m1.ground2.p.v = 0.0;
+//   m1.ground3.p.v = 0.0;
+//   m2.ground1.p.v = 0.0;
+//   m2.ground2.p.v = 0.0;
+//   m2.ground3.p.v = 0.0;
+//   m3.ground1.p.v = 0.0;
+// end ExpandableConnector13;
+// endResult
diff --git a/testsuite/flattening/modelica/scodeinst/Makefile b/testsuite/flattening/modelica/scodeinst/Makefile
index c5cf2c4f9d..0070214958 100644
--- a/testsuite/flattening/modelica/scodeinst/Makefile
+++ b/testsuite/flattening/modelica/scodeinst/Makefile
@@ -450,6 +450,7 @@ ExpandableConnector9.mo \
 ExpandableConnector10.mo \
 ExpandableConnector11.mo \
 ExpandableConnector12.mo \
+ExpandableConnector13.mo \
 ExpandableConnectorComplex1.mo \
 ExpandableConnectorFlow1.mo \
 ExpandableConnectorFlow2.mo \