diff --git a/libutils/ProcessCallStack.cpp b/libutils/ProcessCallStack.cpp
index f837bcb..db07e56 100644
--- a/libutils/ProcessCallStack.cpp
+++ b/libutils/ProcessCallStack.cpp
@@ -90,6 +90,11 @@
         ALOGE("%s: Failed to open %s", __FUNCTION__, path);
     }
 
+    if (procName == NULL) {
+        // Reading /proc/self/task/%d/comm failed due to a race
+        return String8::format("[err-unknown-tid-%d]", tid);
+    }
+
     // Strip ending newline
     strtok(procName, "\n");