diff --git a/runtime/src/kmp_lock.cpp b/runtime/src/kmp_lock.cpp
index 0055116..ed97d36 100644
--- a/runtime/src/kmp_lock.cpp
+++ b/runtime/src/kmp_lock.cpp
@@ -3573,6 +3573,12 @@
         __kmp_indirect_unset = indirect_unset;
         __kmp_indirect_test  = indirect_test;
     }
+    // If the user locks have already been initialized, then return.
+    // Allow the switch between different KMP_CONSISTENCY_CHECK values,
+    // but do not allocate new lock tables if they have already been
+    // allocated.
+    if (__kmp_init_user_locks)
+        return;
 
     // Initialize lock index table
     __kmp_i_lock_table.size = KMP_I_LOCK_CHUNK;
diff --git a/runtime/test/api/kmp_set_defaults_lock_bug.c b/runtime/test/api/kmp_set_defaults_lock_bug.c
new file mode 100644
index 0000000..73a7afb
--- /dev/null
+++ b/runtime/test/api/kmp_set_defaults_lock_bug.c
@@ -0,0 +1,53 @@
+// RUN: %libomp-compile-and-run
+#include <stdio.h>
+#include "omp_testsuite.h"
+/* The bug occurs if the lock table is reallocated after
+   kmp_set_defaults() is called.  If the table is reallocated,
+   then the lock will not point to a valid lock object after the
+   kmp_set_defaults() call.*/
+omp_lock_t lock;
+
+int test_kmp_set_defaults_lock_bug()
+{
+  /* checks that omp_get_num_threads is equal to the number of
+     threads */
+  int nthreads_lib;
+  int nthreads = 0;
+
+  nthreads_lib = -1;
+
+  #pragma omp parallel
+  {
+    omp_set_lock(&lock);
+    nthreads++;
+    omp_unset_lock(&lock);
+    #pragma omp single
+    {
+      nthreads_lib = omp_get_num_threads ();
+    }  /* end of single */
+  } /* end of parallel */
+  kmp_set_defaults("OMP_NUM_THREADS");
+  #pragma omp parallel
+  {
+    omp_set_lock(&lock);
+    nthreads++;
+    omp_unset_lock(&lock);
+  } /* end of parallel */
+
+  return (nthreads == 2*nthreads_lib);
+}
+
+int main()
+{
+  int i;
+  int num_failed=0;
+  omp_init_lock(&lock);
+
+  for(i = 0; i < REPETITIONS; i++) {
+    if(!test_kmp_set_defaults_lock_bug()) {
+      num_failed++;
+    }
+  }
+  omp_destroy_lock(&lock);
+  return num_failed;
+}