diff --git a/go/extractor/util/semver.go b/go/extractor/util/semver.go
index 7cc43541583b..563fbc5a9e34 100644
--- a/go/extractor/util/semver.go
+++ b/go/extractor/util/semver.go
@@ -65,11 +65,29 @@ func NewSemVer(version string) SemVer {
 	// which is compatible with the SemVer specification.
 	rcIndex := strings.Index(version, "rc")
 	if rcIndex != -1 {
-		version = semver.Canonical("v"+version[:rcIndex]) + "-" + version[rcIndex:]
-	}
-
-	// Add the "v" prefix that is required by the `semver` package.
-	if !strings.HasPrefix(version, "v") {
+		var numeric string
+		prerelease := version[rcIndex:]
+
+		// the version string may already contain a "-";
+		// if it does, drop the "-" since we add it back later
+		if version[rcIndex-1] != '-' {
+			numeric = version[:rcIndex]
+		} else {
+			numeric = version[:rcIndex-1]
+		}
+
+		// add a "v" to the numeric part of the version, if it's not already there
+		if !strings.HasPrefix(numeric, "v") {
+			numeric = "v" + numeric
+		}
+
+		// for the semver library to accept a version containing a prerelease,
+		// the numeric part must be canonical; e.g.. "v0-rc1" is not valid and
+		// must be "v0.0.0-rc1" instead.
+		version = semver.Canonical(numeric) + "-" + prerelease
+	} else if !strings.HasPrefix(version, "v") {
+		// Add the "v" prefix that is required by the `semver` package, if
+		// it's not already there.
 		version = "v" + version
 	}
 
diff --git a/go/extractor/util/semver_test.go b/go/extractor/util/semver_test.go
index c721b491acf4..30b755b14452 100644
--- a/go/extractor/util/semver_test.go
+++ b/go/extractor/util/semver_test.go
@@ -22,39 +22,33 @@ func TestNewSemVer(t *testing.T) {
 		{"1.22.3", "v1.22.3"},
 	}
 
-	// Check that we get what we expect for each of the test cases.
-	for _, pair := range testData {
-		result := NewSemVer(pair.Input)
-
-		if result.String() != pair.Expected {
-			t.Errorf("Expected NewSemVer(\"%s\") to return \"%s\", but got \"%s\".", pair.Input, pair.Expected, result)
-		}
-	}
+	// prefixes should not affect the result
+	prefixes := []string{"", "go", "v"}
+	// suffixes
+	suffixes := []string{"", "rc1", "-rc1"}
 
-	// And again, but this time prefixed with "v"
-	for _, pair := range testData {
-		result := NewSemVer("v" + pair.Input)
-
-		if result.String() != pair.Expected {
-			t.Errorf("Expected NewSemVer(\"v%s\") to return \"%s\", but got \"%s\".", pair.Input, pair.Expected, result)
-		}
-	}
-
-	// And again, but this time prefixed with "go"
-	for _, pair := range testData {
-		result := NewSemVer("go" + pair.Input)
-
-		if result.String() != pair.Expected {
-			t.Errorf("Expected NewSemVer(\"go%s\") to return \"%s\", but got \"%s\".", pair.Input, pair.Expected, result)
-		}
-	}
-
-	// And again, but this time with an "rc1" suffix.
+	// Check that we get what we expect for each of the test cases.
 	for _, pair := range testData {
-		result := NewSemVer(pair.Input + "rc1")
-
-		if result.String() != pair.Expected+"-rc1" {
-			t.Errorf("Expected NewSemVer(\"%src1\") to return \"%s\", but got \"%s\".", pair.Input, pair.Expected+"-rc1", result)
+		for _, prefix := range prefixes {
+			for _, suffix := range suffixes {
+				// c
+				input := prefix + pair.Input + suffix
+				result := NewSemVer(input)
+
+				expected := pair.Expected
+				if suffix != "" {
+					expected += "-rc1"
+				}
+
+				if result.String() != expected {
+					t.Errorf(
+						"Expected NewSemVer(\"%s\") to return \"%s\", but got \"%s\".",
+						input,
+						expected,
+						result,
+					)
+				}
+			}
 		}
 	}
 }