Index: src/third_party/libmongocrypt/dist/src/os_posix/os_dll.c
--- src/third_party/libmongocrypt/dist/src/os_posix/os_dll.c.orig
+++ src/third_party/libmongocrypt/dist/src/os_posix/os_dll.c
@@ -113,6 +113,14 @@ mcr_dll_path_result mcr_dll_path(mcr_dll dll) {
 
 // Handled in os_win/os_dll.c
 
+#elif defined(__OpenBSD__)
+
+mcr_dll_path_result mcr_dll_path(mcr_dll dll) {
+    mcr_dll_path_result r;
+    memset(&r, 0, sizeof(r));
+    return r;
+}
+
 #else
 
 #error "Don't know how to do mcr_dll_path() on this platform"
