diff --git a/src/cmd/go/internal/work/gc.go b/src/cmd/go/internal/work/gc.go
index ded751f4d4..1193a5bbfd 100644
--- a/src/cmd/go/internal/work/gc.go
+++ b/src/cmd/go/internal/work/gc.go
@@ -169,7 +169,7 @@ func (gcToolchain) gc(b *Builder, a *Action, archive string, importcfg, embedcfg
 	}
 	// Add -c=N to use concurrent backend compilation, if possible.
 	if c := gcBackendConcurrency(gcflags); c > 1 {
-		gcflags = append(gcflags, fmt.Sprintf("-c=%d", c))
+		defaultGcFlags = append(defaultGcFlags, fmt.Sprintf("-c=%d", c))
 	}
 
 	args := []any{cfg.BuildToolexec, base.Tool("compile"), "-o", ofile, "-trimpath", a.trimpath(), defaultGcFlags, gcflags}
diff --git a/src/cmd/go/testdata/script/build_gcflags_order.txt b/src/cmd/go/testdata/script/build_gcflags_order.txt
index 0ffe1570f6..3725c89eb3 100644
--- a/src/cmd/go/testdata/script/build_gcflags_order.txt
+++ b/src/cmd/go/testdata/script/build_gcflags_order.txt
@@ -4,6 +4,8 @@
 cd m
 go build -n -gcflags=-lang=go1.17
 stderr ' -lang=go1.16.* -lang=go1.17'
+! go build -gcflags='-c 0'
+stderr 'compile: -c must be at least 1, got 0'
 
 -- m/go.mod --
 module example.com