diff --git a/src/functionObjects/field/add/add.C b/src/functionObjects/field/add/add.C
index 7bb9b92fba..c3c94abced 100644
--- a/src/functionObjects/field/add/add.C
+++ b/src/functionObjects/field/add/add.C
@@ -61,6 +61,14 @@ Foam::functionObjects::add::add
     fieldsExpression(name, runTime, dict)
 {
     setResultName("add");
+
+    if (fieldNames_.size() < 2)
+    {
+        FatalIOErrorInFunction(dict)
+            << "At least two field names are required, but only "
+            << fieldNames_.size() << " provided." << nl
+            << exit(FatalIOError);
+    }
 }
 
 
diff --git a/src/functionObjects/field/multiply/multiply.C b/src/functionObjects/field/multiply/multiply.C
index b4b998b590..edb652b4e2 100644
--- a/src/functionObjects/field/multiply/multiply.C
+++ b/src/functionObjects/field/multiply/multiply.C
@@ -51,6 +51,14 @@ Foam::functionObjects::multiply::multiply
     fieldsExpression(name, runTime, dict)
 {
     setResultName("multiply");
+
+    if (fieldNames_.size() < 2)
+    {
+        FatalIOErrorInFunction(dict)
+            << "At least two field names are required, but only "
+            << fieldNames_.size() << " provided." << nl
+            << exit(FatalIOError);
+    }
 }
 
 
diff --git a/src/functionObjects/field/subtract/subtract.C b/src/functionObjects/field/subtract/subtract.C
index cec785d8d3..f41b8cea5a 100644
--- a/src/functionObjects/field/subtract/subtract.C
+++ b/src/functionObjects/field/subtract/subtract.C
@@ -61,6 +61,14 @@ Foam::functionObjects::subtract::subtract
     fieldsExpression(name, runTime, dict)
 {
     setResultName("subtract");
+
+    if (fieldNames_.size() < 2)
+    {
+        FatalIOErrorInFunction(dict)
+            << "At least two field names are required, but only "
+            << fieldNames_.size() << " provided." << nl
+            << exit(FatalIOError);
+    }
 }