diff --git a/src/core/inttypes.c b/src/core/inttypes.c
index b4c999b8..bed6dff1 100644
--- a/src/core/inttypes.c
+++ b/src/core/inttypes.c
@@ -73,13 +73,13 @@ static void *int64_unmarshal(JanetMarshalContext *ctx) {
 
 static void it_s64_tostring(void *p, JanetBuffer *buffer) {
     char str[32];
-    sprintf(str, "%" PRId64, *((int64_t *)p));
+    snprintf(str, sizeof(str), "%" PRId64, *((int64_t *)p));
     janet_buffer_push_cstring(buffer, str);
 }
 
 static void it_u64_tostring(void *p, JanetBuffer *buffer) {
     char str[32];
-    sprintf(str, "%" PRIu64, *((uint64_t *)p));
+    snprintf(str, sizeof(str), "%" PRIu64, *((uint64_t *)p));
     janet_buffer_push_cstring(buffer, str);
 }
 
diff --git a/src/core/pp.c b/src/core/pp.c
index 89ecc141..bba70b6b 100644
--- a/src/core/pp.c
+++ b/src/core/pp.c
@@ -830,7 +830,7 @@ static const char *scanformat(
         if (loc != NULL && *loc != '\0') {
             const char *mapping = get_fmt_mapping(*p2++);
             size_t len = strlen(mapping);
-            strcpy(form, mapping);
+            memcpy(form, mapping, len);
             form += len;
         } else {
             *(form++) = *(p2++);