diff --git a/prometheus/process_collector.go b/prometheus/process_collector.go
index 94b2553..32ac74a 100644
--- a/prometheus/process_collector.go
+++ b/prometheus/process_collector.go
@@ -26,8 +26,11 @@ type processCollector struct {
 }
 
 // NewProcessCollector returns a collector which exports the current state of
-// process metrics including cpu, memory and file descriptor usage as well as
-// the process start time for the given process id under the given namespace.
+// process metrics including CPU, memory and file descriptor usage as well as
+// the process start time for the given process ID under the given namespace.
+//
+// Currently, the collector depends on a Linux-style proc filesystem and
+// therefore only exports metrics for Linux.
 func NewProcessCollector(pid int, namespace string) Collector {
 	return NewProcessCollectorPIDFn(
 		func() (int, error) { return pid, nil },
@@ -35,11 +38,8 @@ func NewProcessCollector(pid int, namespace string) Collector {
 	)
 }
 
-// NewProcessCollectorPIDFn returns a collector which exports the current state
-// of process metrics including cpu, memory and file descriptor usage as well
-// as the process start time under the given namespace. The given pidFn is
-// called on each collect and is used to determine the process to export
-// metrics for.
+// NewProcessCollectorPIDFn works like NewProcessCollector but the process ID is
+// determined on each collect anew by calling the given pidFn function.
 func NewProcessCollectorPIDFn(
 	pidFn func() (int, error),
 	namespace string,
diff --git a/prometheus/registry.go b/prometheus/registry.go
index 73dde7b..bee3703 100644
--- a/prometheus/registry.go
+++ b/prometheus/registry.go
@@ -37,13 +37,13 @@ const (
 // DefaultRegisterer and DefaultGatherer are the implementations of the
 // Registerer and Gatherer interface a number of convenience functions in this
 // package act on. Initially, both variables point to the same Registry, which
-// has a process collector (see NewProcessCollector) and a Go collector (see
-// NewGoCollector) already registered. This approach to keep default instances
-// as global state mirrors the approach of other packages in the Go standard
-// library. Note that there are caveats. Change the variables with caution and
-// only if you understand the consequences. Users who want to avoid global state
-// altogether should not use the convenience function and act on custom
-// instances instead.
+// has a process collector (currently on Linux only, see NewProcessCollector)
+// and a Go collector (see NewGoCollector) already registered. This approach to
+// keep default instances as global state mirrors the approach of other packages
+// in the Go standard library. Note that there are caveats. Change the variables
+// with caution and only if you understand the consequences. Users who want to
+// avoid global state altogether should not use the convenience functions and
+// act on custom instances instead.
 var (
 	defaultRegistry              = NewRegistry()
 	DefaultRegisterer Registerer = defaultRegistry