diff --git a/internal/impl/decode.go b/internal/impl/decode.go
index 85ba1d3..2dcbdec 100644
--- a/internal/impl/decode.go
+++ b/internal/impl/decode.go
@@ -17,6 +17,8 @@
 	piface "google.golang.org/protobuf/runtime/protoiface"
 )
 
+var errDecode = errors.New("cannot parse invalid wire-format data")
+
 type unmarshalOptions struct {
 	flags    protoiface.UnmarshalInputFlags
 	resolver interface {
@@ -100,13 +102,13 @@
 			var n int
 			tag, n = protowire.ConsumeVarint(b)
 			if n < 0 {
-				return out, protowire.ParseError(n)
+				return out, errDecode
 			}
 			b = b[n:]
 		}
 		var num protowire.Number
 		if n := tag >> 3; n < uint64(protowire.MinValidNumber) || n > uint64(protowire.MaxValidNumber) {
-			return out, errors.New("invalid field number")
+			return out, errDecode
 		} else {
 			num = protowire.Number(n)
 		}
@@ -114,7 +116,7 @@
 
 		if wtyp == protowire.EndGroupType {
 			if num != groupTag {
-				return out, errors.New("mismatching end group marker")
+				return out, errDecode
 			}
 			groupTag = 0
 			break
@@ -170,7 +172,7 @@
 			}
 			n = protowire.ConsumeFieldValue(num, wtyp, b)
 			if n < 0 {
-				return out, protowire.ParseError(n)
+				return out, errDecode
 			}
 			if !opts.DiscardUnknown() && mi.unknownOffset.IsValid() {
 				u := p.Apply(mi.unknownOffset).Bytes()
@@ -181,7 +183,7 @@
 		b = b[n:]
 	}
 	if groupTag != 0 {
-		return out, errors.New("missing end group marker")
+		return out, errDecode
 	}
 	if mi.numRequiredFields > 0 && bits.OnesCount64(requiredMask) != int(mi.numRequiredFields) {
 		initialized = false
@@ -221,7 +223,7 @@
 					return out, nil
 				}
 			case ValidationInvalid:
-				return out, errors.New("invalid wire format")
+				return out, errDecode
 			case ValidationUnknown:
 			}
 		}