diff --git a/src/theories.c b/src/theories.c
index 7cc86d9..3bf0f5b 100644
--- a/src/theories.c
+++ b/src/theories.c
@@ -186,7 +186,7 @@ static void concat_arg(char (*msg)[4096], struct criterion_datapoints *dps, size
 void cr_theory_main(struct criterion_datapoints *dps, size_t datapoints, void (*fnptr)(void)) {
     struct criterion_theory_context *ctx = cr_theory_init();
 
-    size_t *indices = malloc(datapoints);
+    size_t *indices = malloc(sizeof (size_t) * datapoints);
     memset(indices, 0, datapoints * sizeof (size_t));
 
     bool has_next = true;