diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index ca9f629..0821ca4 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -4794,12 +4794,21 @@
     if (const auto displayId = getInternalDisplayIdLocked();
         displayId && getHwComposer().isConnected(*displayId)) {
         const auto activeConfig = getHwComposer().getActiveConfig(*displayId);
+        std::string fps, xDpi, yDpi;
+        if (activeConfig) {
+            fps = std::to_string(1e9 / getHwComposer().getDisplayVsyncPeriod(*displayId)) + " fps";
+            xDpi = activeConfig->getDpiX();
+            yDpi = activeConfig->getDpiY();
+        } else {
+            fps = "unknown";
+            xDpi = "unknown";
+            yDpi = "unknown";
+        }
         StringAppendF(&result,
-                      "  refresh-rate              : %f fps\n"
-                      "  x-dpi                     : %f\n"
-                      "  y-dpi                     : %f\n",
-                      1e9 / getHwComposer().getDisplayVsyncPeriod(*displayId),
-                      activeConfig->getDpiX(), activeConfig->getDpiY());
+                      "  refresh-rate              : %s\n"
+                      "  x-dpi                     : %s\n"
+                      "  y-dpi                     : %s\n",
+                      fps.c_str(), xDpi.c_str(), yDpi.c_str());
     }
 
     StringAppendF(&result, "  transaction time: %f us\n", inTransactionDuration / 1000.0);