diff --git a/src/pulse/context.c b/src/pulse/context.c
index 8722f3503..a63265df3 100644
--- a/src/pulse/context.c
+++ b/src/pulse/context.c
@@ -1331,7 +1331,7 @@ const char* pa_context_get_server(pa_context *c) {
     return c->server;
 }
 
-uint32_t pa_context_get_protocol_version(pa_context *c) {
+uint32_t pa_context_get_protocol_version(const pa_context *c) {
     return PA_PROTOCOL_VERSION;
 }
 
diff --git a/src/pulse/context.h b/src/pulse/context.h
index 9d4c926e8..d79661f58 100644
--- a/src/pulse/context.h
+++ b/src/pulse/context.h
@@ -236,7 +236,7 @@ pa_operation* pa_context_set_name(pa_context *c, const char *name, pa_context_su
 const char* pa_context_get_server(pa_context *c);
 
 /** Return the protocol version of the library. */
-uint32_t pa_context_get_protocol_version(pa_context *c);
+uint32_t pa_context_get_protocol_version(const pa_context *c);
 
 /** Return the protocol version of the connected server.
  * Returns PA_INVALID_INDEX on error. */