diff --git a/src/cmd/cover/cfg_test.go b/src/cmd/cover/cfg_test.go
index a3576ddf01..9497800d0c 100644
--- a/src/cmd/cover/cfg_test.go
+++ b/src/cmd/cover/cfg_test.go
@@ -129,7 +129,6 @@ func TestCoverWithCfg(t *testing.T) {
 		},
 	}
 
-	tag := "first"
 	var incfg string
 	for _, scenario := range scenarios {
 		// Instrument package "a", producing a set of instrumented output
@@ -138,6 +137,7 @@ func TestCoverWithCfg(t *testing.T) {
 		pname := "a"
 		mode := scenario.mode
 		gran := scenario.gran
+		tag := mode + "_" + gran
 		incfg = writePkgConfig(t, instdira, tag, ppath, pname, gran)
 		ofs, outcfg, _ := runPkgCover(t, instdira, tag, incfg, mode,
 			pfiles("a"), false)
@@ -158,6 +158,7 @@ func TestCoverWithCfg(t *testing.T) {
 	// Expect error if config file inaccessible/unreadable.
 	mode := "atomic"
 	errExpected := true
+	tag := "errors"
 	_, _, errmsg := runPkgCover(t, instdira, tag, "/not/a/file", mode,
 		pfiles("a"), errExpected)
 	want := "error reading pkgconfig file"
diff --git a/src/cmd/cover/cover.go b/src/cmd/cover/cover.go
index 60cfcb5bc2..25574de773 100644
--- a/src/cmd/cover/cover.go
+++ b/src/cmd/cover/cover.go
@@ -426,7 +426,9 @@ func (f *File) Visit(node ast.Node) ast.Visitor {
 		if *pkgcfg != "" {
 			f.preFunc(n, fname)
 		}
-		ast.Walk(f, n.Body)
+		if pkgconfig.Granularity != "perfunc" {
+			ast.Walk(f, n.Body)
+		}
 		if *pkgcfg != "" {
 			flit := true
 			f.postFunc(n, fname, flit, n.Body)
@@ -465,6 +467,13 @@ func (f *File) preFunc(fn ast.Node, fname string) {
 }
 
 func (f *File) postFunc(fn ast.Node, funcname string, flit bool, body *ast.BlockStmt) {
+
+	// Tack on single counter write if we are in "perfunc" mode.
+	singleCtr := ""
+	if pkgconfig.Granularity == "perfunc" {
+		singleCtr = "; " + f.newCounter(fn.Pos(), fn.Pos(), 1)
+	}
+
 	// record the length of the counter var required.
 	nc := len(f.fn.units) + coverage.FirstCtrOffset
 	f.pkg.counterLengths = append(f.pkg.counterLengths, nc)
@@ -504,12 +513,16 @@ func (f *File) postFunc(fn ast.Node, funcname string, flit bool, body *ast.Block
 	cv := f.fn.counterVar
 	regHook := hookWrite(cv, 0, strconv.Itoa(len(f.fn.units))) + " ; " +
 		hookWrite(cv, 1, mkPackageIdExpression()) + " ; " +
-		hookWrite(cv, 2, strconv.Itoa(int(funcId)))
+		hookWrite(cv, 2, strconv.Itoa(int(funcId))) + singleCtr
+
+	// Insert the registration sequence into the function. We want this sequence to
+	// appear before any counter updates, so use a hack to ensure that this edit
+	// applies before the edit corresponding to the prolog counter update.
 
-	// Insert the registration sequence into the function.
 	boff := f.offset(body.Pos())
-	ipos := f.fset.File(body.Pos()).Pos(boff + 1)
-	f.edit.Insert(f.offset(ipos), regHook+" ; ")
+	ipos := f.fset.File(body.Pos()).Pos(boff)
+	ip := f.offset(ipos)
+	f.edit.Replace(ip, ip+1, string(f.content[ipos-1])+regHook+" ; ")
 
 	f.fn.counterVar = ""
 }
@@ -661,7 +674,6 @@ func (f *File) newCounter(start, end token.Pos, numStmt int) string {
 			NxStmts: uint32(numStmt),
 		}
 		f.fn.units = append(f.fn.units, unit)
-
 	} else {
 		stmt = counterStmt(f, fmt.Sprintf("%s.Count[%d]", *varVar,
 			len(f.blocks)))