diff --git a/dudect/fixture.c b/dudect/fixture.c
index 65d6ae4c9..c2e273a7a 100644
--- a/dudect/fixture.c
+++ b/dudect/fixture.c
@@ -187,7 +187,7 @@ static bool doit(int mode)
     int64_t *percentiles = calloc(NUM_PERCENTILES, sizeof(int64_t));
 
     if (!before_ticks || !after_ticks || !exec_times || !classes ||
-        !input_data) {
+        !input_data || !percentiles) {
         die();
     }
 
@@ -213,8 +213,13 @@ static void init_once(void)
 {
     init_dut();
     for (size_t i = 0; i < DUDECT_TESTS; i++) {
-        ctxs[i] = malloc(sizeof(t_context_t));
-        t_init(ctxs[i]);
+        /* Check if ctxs[i] is unallocated to prevent repeated memory
+         * allocations.
+         */
+        if (!ctxs[i]) {
+            ctxs[i] = malloc(sizeof(t_context_t));
+            t_init(ctxs[i]);
+        }
     }
 }
 
@@ -222,9 +227,10 @@ static bool test_const(char *text, int mode)
 {
     bool result = false;
 
+    init_once();
+
     for (int cnt = 0; cnt < TEST_TRIES; ++cnt) {
         printf("Testing %s...(%d/%d)\n\n", text, cnt, TEST_TRIES);
-        init_once();
         for (int i = 0; i < ENOUGH_MEASURE / (N_MEASURES - DROP_SIZE * 2) + 1;
              ++i)
             result = doit(mode);
@@ -235,6 +241,7 @@ static bool test_const(char *text, int mode)
 
     for (size_t i = 0; i < DUDECT_TESTS; i++) {
         free(ctxs[i]);
+        ctxs[i] = NULL;
     }
 
     return result;