diff --git a/src/parsers/conan.rs b/src/parsers/conan.rs
index 2f79d1184..4ba63e7bc 100644
--- a/src/parsers/conan.rs
+++ b/src/parsers/conan.rs
@@ -30,7 +30,6 @@
 use std::path::Path;
 
 use crate::parser_warn as warn;
-use packageurl::PackageUrl;
 use ruff_python_ast as ast;
 use ruff_python_parser::parse_module;
 use serde_json::Value;
@@ -477,16 +476,9 @@ fn parse_conan_reference(ref_str: &str) -> Option<Dependency> {
 
     // A range constraint is not a PURL version, so ranged and bare references
     // both fall through to a name-only PURL and keep the constraint in
-    // `extracted_requirement`.
-    let purl = version
-        .as_deref()
-        .and_then(|v| {
-            PackageUrl::new("conan", name).ok().map(|mut p| {
-                let _ = p.with_version(v);
-                p.to_string()
-            })
-        })
-        .unwrap_or_else(|| format!("pkg:conan/{}", name));
+    // `extracted_requirement`. Both forms go through the encoder — the
+    // hand-formatted fallback left a name like `my pkg` unencoded.
+    let purl = crate::parsers::utils::simple_purl("conan", name, version.as_deref());
 
     let is_pinned = version_spec
         .as_ref()
@@ -494,7 +486,7 @@ fn parse_conan_reference(ref_str: &str) -> Option<Dependency> {
         .unwrap_or(false);
 
     Some(Dependency {
-        purl: Some(truncate_field(purl)),
+        purl: purl.map(truncate_field),
         extracted_requirement: version_spec,
         scope: Some("install".to_string()),
         is_runtime: Some(true),
diff --git a/src/parsers/conan_test.rs b/src/parsers/conan_test.rs
index dab45dd73..0456e9c53 100644
--- a/src/parsers/conan_test.rs
+++ b/src/parsers/conan_test.rs
@@ -6,6 +6,7 @@
 use crate::models::{DatasourceId, PackageType};
 
 use std::path::PathBuf;
+use std::str::FromStr;
 
 use super::PackageParser;
 use super::conan::{ConanFilePyParser, ConanLockParser, ConanfileTxtParser};
@@ -195,6 +196,45 @@ fn test_conanfile_txt_basic() {
     assert_eq!(result.datasource_id, Some(DatasourceId::ConanConanFileTxt));
 }
 
+#[test]
+fn test_conan_reference_purls_are_encoded() {
+    use std::io::Write;
+
+    // A reference with a range constraint yields no PURL version, so it took the
+    // hand-formatted path where a name was spliced in unencoded.
+    let dir = std::env::temp_dir().join(format!(
+        "provenant-conan-{}",
+        std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .expect("system time should be after epoch")
+            .as_nanos()
+    ));
+    std::fs::create_dir_all(&dir).expect("create temp dir");
+    let path = dir.join("conanfile.txt");
+    let mut file = std::fs::File::create(&path).expect("create conanfile.txt");
+    writeln!(file, "[requires]\nmy pkg/[>=1.0]\nplain/1.0").expect("write conanfile.txt");
+
+    let result = ConanfileTxtParser::extract_first_package(&path);
+    let purls: Vec<&str> = result
+        .dependencies
+        .iter()
+        .filter_map(|dependency| dependency.purl.as_deref())
+        .collect();
+
+    assert!(
+        purls.contains(&"pkg:conan/my%20pkg"),
+        "the ranged reference should encode its name, got {purls:?}"
+    );
+    assert!(purls.contains(&"pkg:conan/plain@1.0"));
+
+    for purl in &purls {
+        let parsed = packageurl::PackageUrl::from_str(purl).expect("purl should parse");
+        assert_eq!(parsed.to_string(), *purl, "{purl} should round-trip");
+    }
+
+    std::fs::remove_dir_all(&dir).ok();
+}
+
 #[test]
 fn test_conan_lock_parser_is_match() {
     assert!(ConanLockParser::is_match(&PathBuf::from("conan.lock")));
diff --git a/src/parsers/opam.rs b/src/parsers/opam.rs
index 5781b456e..8cab1d853 100644
--- a/src/parsers/opam.rs
+++ b/src/parsers/opam.rs
@@ -228,11 +228,9 @@ fn build_opam_urls(
         _ => None,
     };
 
-    let purl = match (name, version) {
-        (Some(n), Some(v)) => Some(format!("pkg:opam/{}@{}", n, v)),
-        (Some(n), None) => Some(format!("pkg:opam/{}", n)),
-        _ => None,
-    };
+    let purl = name
+        .as_deref()
+        .and_then(|n| crate::parsers::utils::simple_purl("opam", n, version.as_deref()));
 
     (repository_homepage_url, api_data_url, purl)
 }
@@ -660,7 +658,7 @@ fn extract_parties(authors: &[String], maintainers: &[String]) -> Vec<Party> {
 fn extract_dependencies(deps: &[(String, String)]) -> Vec<Dependency> {
     deps.iter()
         .map(|(name, version_constraint)| Dependency {
-            purl: Some(truncate_field(format!("pkg:opam/{}", name))),
+            purl: crate::parsers::utils::simple_purl("opam", name, None).map(truncate_field),
             extracted_requirement: Some(truncate_field(version_constraint.clone())),
             scope: Some("dependency".to_string()),
             is_runtime: Some(true),
@@ -696,6 +694,41 @@ mod tests {
         assert!(!OpamParser::is_match(path));
     }
 
+    #[test]
+    fn test_opam_purls_are_encoded_rather_than_formatted() {
+        // Names come from a quoted opam field, so anything but a quote reaches the
+        // PURL. Splicing them in unencoded produced strings that either failed to
+        // parse or silently changed meaning: a `/` became a namespace separator
+        // and text after a `#` became a subpath.
+        use std::str::FromStr;
+
+        for (name, version, expected) in [
+            ("conf gmp", None, "pkg:opam/conf%20gmp"),
+            ("ocaml/evil", None, "pkg:opam/ocaml%2Fevil"),
+            ("sharp#frag", None, "pkg:opam/sharp%23frag"),
+            // Already-percent-encoded text is data, not encoding: the real name is
+            // the literal six characters, so it must survive a round trip.
+            ("pct%20", None, "pkg:opam/pct%2520"),
+            ("my pkg", Some("1.0 beta"), "pkg:opam/my%20pkg@1.0%20beta"),
+        ] {
+            let purl = crate::parsers::utils::simple_purl("opam", name, version)
+                .expect("a non-empty name should yield a purl");
+            assert_eq!(purl, expected);
+
+            let parsed = packageurl::PackageUrl::from_str(&purl).expect("purl should parse");
+            assert_eq!(parsed.name(), name);
+            assert_eq!(parsed.namespace(), None);
+            assert_eq!(parsed.subpath(), None);
+            assert_eq!(parsed.version(), version);
+            assert_eq!(parsed.to_string(), purl, "purl should round-trip");
+        }
+
+        assert_eq!(
+            crate::parsers::utils::simple_purl("opam", "   ", None),
+            None
+        );
+    }
+
     #[test]
     fn test_parse_key_value() {
         let (key, value) = parse_key_value("name: \"js_of_ocaml\"").unwrap();
diff --git a/src/parsers/swift_show_dependencies.rs b/src/parsers/swift_show_dependencies.rs
index 98a74e186..8a6fcd3f6 100644
--- a/src/parsers/swift_show_dependencies.rs
+++ b/src/parsers/swift_show_dependencies.rs
@@ -248,12 +248,7 @@ fn build_dependency(
 fn create_dependency_purl(dep: &SwiftDependency, version: Option<&str>) -> Option<String> {
     let url = dep.url.as_deref()?;
     let (namespace, name) = parse_url_namespace_and_name(url)?;
-    let mut purl = format!("pkg:swift/{}/{}", namespace, name);
-    if let Some(version) = version {
-        purl.push('@');
-        purl.push_str(version);
-    }
-    Some(purl)
+    crate::parsers::utils::namespaced_purl("swift", &namespace, &name, version)
 }
 
 /// As with dependencies, the root package needs a namespace derived from its
@@ -268,13 +263,7 @@ fn create_root_purl(
         return None;
     }
     let (namespace, _) = parse_url_namespace_and_name(url?)?;
-
-    let mut purl = format!("pkg:swift/{}/{}", namespace, name);
-    if let Some(version) = version {
-        purl.push('@');
-        purl.push_str(version);
-    }
-    Some(purl)
+    crate::parsers::utils::namespaced_purl("swift", &namespace, name, version)
 }
 
 fn normalize_version(version: Option<String>) -> Option<String> {
diff --git a/src/parsers/utils.rs b/src/parsers/utils.rs
index 92df48796..f025dfa41 100644
--- a/src/parsers/utils.rs
+++ b/src/parsers/utils.rs
@@ -297,6 +297,58 @@ pub fn url_authority_host(authority: &str) -> &str {
         .unwrap_or(authority)
 }
 
+/// Builds a PURL for a type that takes no namespace, running the name and version
+/// through the crate's encoder.
+///
+/// Parsers that assemble a PURL with `format!` splice unvalidated text straight
+/// into it, so a name carrying a space, `?`, `#` or `/` yields a string that
+/// either fails to parse or silently reinterprets — a `/` in the name becomes a
+/// namespace separator, and text after a `#` becomes a subpath. Returns `None`
+/// when the components cannot form a PURL, which is the honest outcome: the
+/// declared text is still reported in the fields that carry it.
+///
+/// Only for types the crate does not rewrite. It lowercases names for
+/// `bitbucket`, `deb`, `github`, `hex`, `npm` and `pypi`, so those need a
+/// deliberate decision about case rather than this helper.
+pub fn simple_purl(package_type: &str, name: &str, version: Option<&str>) -> Option<String> {
+    let name = name.trim();
+    if name.is_empty() {
+        return None;
+    }
+
+    let mut package_url = PackageUrl::new(package_type.to_string(), name.to_string()).ok()?;
+    if let Some(version) = version.map(str::trim).filter(|value| !value.is_empty()) {
+        package_url.with_version(version.to_string()).ok()?;
+    }
+    Some(package_url.to_string())
+}
+
+/// Builds a PURL for a type that carries a namespace, running every component
+/// through the crate's encoder.
+///
+/// The namespace keeps its `/` separators — its segments are path parts — while
+/// the name and version are encoded, which is what hand-formatting missed.
+///
+/// Same caveat as [`simple_purl`]: not for the types the crate rewrites.
+pub fn namespaced_purl(
+    package_type: &str,
+    namespace: &str,
+    name: &str,
+    version: Option<&str>,
+) -> Option<String> {
+    let (namespace, name) = (namespace.trim(), name.trim());
+    if namespace.is_empty() || name.is_empty() {
+        return None;
+    }
+
+    let mut package_url = PackageUrl::new(package_type.to_string(), name.to_string()).ok()?;
+    package_url.with_namespace(namespace.to_string()).ok()?;
+    if let Some(version) = version.map(str::trim).filter(|value| !value.is_empty()) {
+        package_url.with_version(version.to_string()).ok()?;
+    }
+    Some(package_url.to_string())
+}
+
 /// Creates a correctly-formatted npm Package URL for scoped or regular packages.
 ///
 /// Handles namespace encoding for scoped packages (e.g., `@babel/core`) and ensures