diff --git a/src/lib/crypto/backend_version.cpp b/src/lib/crypto/backend_version.cpp
index 43d8d4f516..86aed98dfd 100644
--- a/src/lib/crypto/backend_version.cpp
+++ b/src/lib/crypto/backend_version.cpp
@@ -84,7 +84,9 @@ backend_version()
             return "unknown";
         }
     }
-    if (regexec(&r, ver, 5, matches, 0) != 0) {
+    int res = regexec(&r, ver, 5, matches, 0);
+    if (res != 0) {
+        RNP_LOG("regexec() failed on %s: %d", ver, res);
         return "unknown";
     }
     assert(sizeof(version) > matches[1].rm_eo - matches[1].rm_so);
@@ -95,6 +97,7 @@ backend_version()
     std::smatch       result;
     std::string       ver = OpenSSL_version(OPENSSL_VERSION);
     if (!std::regex_search(ver, result, re)) {
+        RNP_LOG("std::regex_search failed on \"%s\"", ver);
         return "unknown";
     }
     assert(sizeof(version) > result[1].str().size());