diff --git a/src/core/operations/FromBCD.mjs b/src/core/operations/FromBCD.mjs
index 8fa990a4..5be1b911 100644
--- a/src/core/operations/FromBCD.mjs
+++ b/src/core/operations/FromBCD.mjs
@@ -73,6 +73,9 @@ class FromBCD extends Operation {
         let output = "",
             byteArray;
 
+        if (encoding === undefined)
+            throw new OperationError("Invalid encoding scheme");
+
         // Normalise the input
         switch (inputFormat) {
             case "Nibbles":
diff --git a/src/core/operations/ToBCD.mjs b/src/core/operations/ToBCD.mjs
index 3908742c..4e880400 100644
--- a/src/core/operations/ToBCD.mjs
+++ b/src/core/operations/ToBCD.mjs
@@ -67,6 +67,9 @@ class ToBCD extends Operation {
             signed = args[2],
             outputFormat = args[3];
 
+        if (encoding === undefined)
+            throw new OperationError("Invalid encoding scheme");
+
         // Split input number up into separate digits
         const digits = input.toFixed().split("");
 
diff --git a/tests/operations/tests/BCD.mjs b/tests/operations/tests/BCD.mjs
index c6715e56..53d46948 100644
--- a/tests/operations/tests/BCD.mjs
+++ b/tests/operations/tests/BCD.mjs
@@ -100,4 +100,26 @@ TestRegister.addTests([
             }
         ]
     },
+    {
+        name: "To BCD: invalid (empty) encoding scheme",
+        input: "43",
+        expectedOutput: "Invalid encoding scheme",
+        recipeConfig: [
+            {
+                "op": "To BCD",
+                "args": ["", true, false, "Nibbles"]
+            }
+        ]
+    },
+    {
+        name: "From BCD: invalid (empty) encoding scheme",
+        input: "0100 0011",
+        expectedOutput: "Invalid encoding scheme",
+        recipeConfig: [
+            {
+                "op": "From BCD",
+                "args": ["", true, false, "Nibbles"]
+            }
+        ]
+    },
 ]);