diff --git a/leopard.nim b/leopard.nim
index 77b78bc..84dad5c 100644
--- a/leopard.nim
+++ b/leopard.nim
@@ -16,6 +16,8 @@ const
   LeopardNotEnoughDataMsg = "Buffer counts are too low"
 
   MinBufferSize* = 64.uint
+  MinSymbols* = 1.uint
+  MaxTotalSymbols* = 65536.uint
 
 type
   Data* = seq[seq[byte]]
@@ -61,11 +63,17 @@ type
 # data symbols     = 239
 # parity symbols   = 255 - 239 = 16
 
+func isValid*(code: ReedSolomonCode): bool =
+  not ((code.codeword - code.data != code.parity) or
+       (code.parity > code.data) or (code.codeword < MinSymbols + 1) or
+       (code.data < MinSymbols) or (code.parity < MinSymbols) or
+       (code.codeword > MaxTotalSymbols))
+
 proc RS*(codeword, data: Positive): ReedSolomonCode =
   var
     parity = codeword - data
 
-  if parity <= 0: parity = 0
+  if parity < 0: parity = 0
   (codeword: codeword.uint, data: data.uint, parity: parity.uint)
 
 when (NimMajor, NimMinor, NimPatch) < (1, 4, 0):
@@ -116,7 +124,7 @@ proc leoInit*() =
 
 proc encode*(code: ReedSolomonCode, data: Data):
     Result[ParityData, LeopardError] =
-  if code.parity < 1 or code.parity > code.data:
+  if not code.isValid:
     return err LeopardError(code: LeopardBadCode, msg: LeopardBadCodeMsg)
 
   var
@@ -194,7 +202,7 @@ proc encode*(code: ReedSolomonCode, data: Data):
 
 proc decode*(code: ReedSolomonCode, data: Data, parityData: ParityData,
     symbolBytes: uint): Result[Data, LeopardError] =
-  if code.parity < 1 or code.parity > code.data:
+  if not code.isValid:
     return err LeopardError(code: LeopardBadCode, msg: LeopardBadCodeMsg)
 
   var
diff --git a/tests/test_leopard.nim b/tests/test_leopard.nim
index 1e4d496..c9c7d81 100644
--- a/tests/test_leopard.nim
+++ b/tests/test_leopard.nim
@@ -19,6 +19,33 @@ proc genData(outerLen, innerLen: uint): Data =
 var
   initialized = false
 
+suite "Helpers":
+  test "isValid should return false if RS code is nonsensical or is invalid per Leopard-RS":
+    var
+      rsCode = (codeword: 8.uint, data: 5.uint, parity: 1.uint)
+
+    check: not rsCode.isValid
+
+    rsCode = RS(110,10)
+
+    check: not rsCode.isValid
+
+    rsCode = RS(1,1)
+
+    check: not rsCode.isValid
+
+    rsCode = (codeword: 2.uint, data: 0.uint, parity: 2.uint)
+
+    check: not rsCode.isValid
+
+    rsCode = RS(2,2)
+
+    check: not rsCode.isValid
+
+    rsCode = RS(65537,65409)
+
+    check: not rsCode.isValid
+
 suite "Initialization":
   test "encode and decode should fail if Leopard-RS is not initialized":
     let
@@ -53,7 +80,7 @@ suite "Initialization":
     check: initialized
 
 suite "Encoder":
-  test "should fail if RS code is nonsensical or is so per Leopard-RS":
+  test "should fail if RS code is nonsensical or is invalid per Leopard-RS":
     check: initialized
     if not initialized: return
 
@@ -61,7 +88,7 @@ suite "Encoder":
       symbolBytes = MinBufferSize
 
     var
-      rsCode = RS(5,5)
+      rsCode = RS(110,10)
       data = genData(rsCode.data, symbolBytes)
       encodeRes = rsCode.encode data
 
@@ -69,22 +96,6 @@ suite "Encoder":
     if encodeRes.isErr:
       check: encodeRes.error.code == LeopardBadCode
 
-    rsCode = RS(5,10)
-    data = genData(rsCode.data, symbolBytes)
-    encodeRes = rsCode.encode data
-
-    check: encodeRes.isErr
-    if encodeRes.isErr:
-      check: encodeRes.error.code == LeopardBadCode
-
-    rsCode = RS(110,10)
-    data = genData(rsCode.data, symbolBytes)
-    encodeRes = rsCode.encode data
-
-    check: encodeRes.isErr
-    if encodeRes.isErr:
-      check: encodeRes.error.code == LeopardBadCode
-
   test "should fail if outer length of data does not match the RS code":
     check: initialized
     if not initialized: return
@@ -185,7 +196,7 @@ suite "Encoder":
     check: encodeRes.isOk
 
 suite "Decoder":
-  test "should fail if RS code is nonsensical or is so per Leopard-RS":
+  test "should fail if RS code is nonsensical or is invalid per Leopard-RS":
     check: initialized
     if not initialized: return
 
@@ -193,7 +204,7 @@ suite "Decoder":
       symbolBytes = MinBufferSize
 
     var
-      rsCode = RS(5,5)
+      rsCode = RS(110,10)
       data = genData(rsCode.data, symbolBytes)
       parityData: ParityData
       decodeRes = rsCode.decode(data, parityData, symbolBytes)
@@ -202,22 +213,6 @@ suite "Decoder":
     if decodeRes.isErr:
       check: decodeRes.error.code == LeopardBadCode
 
-    rsCode = RS(5,10)
-    data = genData(rsCode.data, symbolBytes)
-    decodeRes = rsCode.decode(data, parityData, symbolBytes)
-
-    check: decodeRes.isErr
-    if decodeRes.isErr:
-      check: decodeRes.error.code == LeopardBadCode
-
-    rsCode = RS(110,10)
-    data = genData(rsCode.data, symbolBytes)
-    decodeRes = rsCode.decode(data, parityData, symbolBytes)
-
-    check: decodeRes.isErr
-    if decodeRes.isErr:
-      check: decodeRes.error.code == LeopardBadCode
-
   test "should fail if outer length of data does not match the RS code":
     check: initialized
     if not initialized: return