diff --git a/pkg/cmd/debug.go b/pkg/cmd/debug.go
index c0d47531..ae592b5b 100644
--- a/pkg/cmd/debug.go
+++ b/pkg/cmd/debug.go
@@ -106,6 +106,7 @@ func printStats(hirSchema *hir.Schema, hir bool, mir bool, air bool) {
 		for j := 0; j < len(schemas); j++ {
 			row[j+1] = ith.summary(schemas[j])
 		}
+
 		tbl.SetRow(i, row...)
 	}
 	//
diff --git a/pkg/cmd/trace.go b/pkg/cmd/trace.go
index 89edc9a0..03065cde 100644
--- a/pkg/cmd/trace.go
+++ b/pkg/cmd/trace.go
@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"math"
 	"os"
-	"strings"
+	"regexp"
 
 	"github.com/consensys/go-corset/pkg/trace"
 	"github.com/consensys/go-corset/pkg/util"
@@ -63,23 +63,30 @@ func init() {
 	traceCmd.Flags().UintP("end", "e", math.MaxUint, "filter out this and all following rows")
 	traceCmd.Flags().Uint("max-width", 32, "specify maximum display width for a column")
 	traceCmd.Flags().StringP("out", "o", "", "Specify output file to write trace")
-	traceCmd.Flags().StringP("filter", "f", "", "Filter columns beginning with prefix")
+	traceCmd.Flags().StringP("filter", "f", "", "Filter columns matching regex")
 }
 
 // Construct a new trace containing only those columns from the original who
 // name begins with the given prefix.
-func filterColumns(cols []trace.RawColumn, prefix string) []trace.RawColumn {
+func filterColumns(cols []trace.RawColumn, regex string) []trace.RawColumn {
+	r, err := regexp.Compile(regex)
+	// Check for error
+	if err != nil {
+		panic(err)
+	}
+	//
 	ncols := make([]trace.RawColumn, 0)
 	// Now create the columns.
 	for i := 0; i < len(cols); i++ {
 		name := trace.QualifiedColumnName(cols[i].Module, cols[i].Name)
-		if strings.HasPrefix(name, prefix) {
+		if r.MatchString(name) {
 			ncols = append(ncols, cols[i])
 		}
 	}
 	// Done
 	return ncols
 }
+
 func printTrace(start uint, end uint, max_width uint, cols []trace.RawColumn) {
 	n := uint(len(cols))
 	height := min(maxHeightColumns(cols), end) - start
@@ -119,6 +126,7 @@ func listColumns(tr []trace.RawColumn) {
 		for j := 0; j < len(colSummarisers); j++ {
 			row[j+1] = colSummarisers[j].summary(tr[i])
 		}
+
 		tbl.SetRow(i, row...)
 	}
 	//
diff --git a/pkg/test/ir_test.go b/pkg/test/ir_test.go
index 4ad18faf..393e2373 100644
--- a/pkg/test/ir_test.go
+++ b/pkg/test/ir_test.go
@@ -553,14 +553,12 @@ func checkTrace(t *testing.T, inputs []trace.RawColumn, expand bool, id traceId,
 		// Process what happened versus what was supposed to happen.
 		if !accepted && id.expected {
 			//table.PrintTrace(tr)
-			msg := fmt.Sprintf("Trace rejected incorrectly (%s, %s.accepts, line %d with padding %d): %s",
+			t.Errorf("Trace rejected incorrectly (%s, %s.accepts, line %d with padding %d): %s",
 				id.ir, id.test, id.line, id.padding, errs)
-			t.Errorf(msg)
 		} else if accepted && !id.expected {
 			//printTrace(tr)
-			msg := fmt.Sprintf("Trace accepted incorrectly (%s, %s.rejects, line %d with padding %d)",
+			t.Errorf("Trace accepted incorrectly (%s, %s.rejects, line %d with padding %d)",
 				id.ir, id.test, id.line, id.padding)
-			t.Errorf(msg)
 		}
 	}
 }
diff --git a/pkg/trace/array_trace.go b/pkg/trace/array_trace.go
index c4d129f7..0313469a 100644
--- a/pkg/trace/array_trace.go
+++ b/pkg/trace/array_trace.go
@@ -119,9 +119,11 @@ func (p *ArrayTrace) String() string {
 
 				id.WriteString(jth.String())
 			}
+
 			id.WriteString("}")
 		}
 	}
+
 	id.WriteString("}")
 	//
 	return id.String()
diff --git a/pkg/trace/json/writer.go b/pkg/trace/json/writer.go
index 09382688..df8d9180 100644
--- a/pkg/trace/json/writer.go
+++ b/pkg/trace/json/writer.go
@@ -37,6 +37,7 @@ func ToJsonString(columns []trace.RawColumn) string {
 			jth := data.Get(j)
 			builder.WriteString(jth.String())
 		}
+
 		builder.WriteString("]")
 	}
 	//
diff --git a/pkg/trace/printer.go b/pkg/trace/printer.go
index 7848e3d7..0eb9f93c 100644
--- a/pkg/trace/printer.go
+++ b/pkg/trace/printer.go
@@ -224,6 +224,7 @@ func printHorizontalRule(widths []int) {
 		for i := 0; i < w; i++ {
 			fmt.Print("-")
 		}
+
 		fmt.Print("-+")
 	}