diff --git a/src/core/buffer.c b/src/core/buffer.c
index 2983a0fc..085133ef 100644
--- a/src/core/buffer.c
+++ b/src/core/buffer.c
@@ -371,17 +371,15 @@ JANET_CORE_FN(cfun_buffer_push_uint16,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        uint16_t data;
-        uint8_t bytes[2];
-    } u;
-    u.data = janet_getuinteger16(argv, 2);
+    uint16_t data = janet_getuinteger16(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse) {
-        uint8_t temp = u.bytes[1];
-        u.bytes[1] = u.bytes[0];
-        u.bytes[0] = temp;
+        uint8_t temp = bytes[1];
+        bytes[1] = bytes[0];
+        bytes[0] = temp;
     }
-    janet_buffer_push_u16(buffer, *(uint16_t *) u.bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
@@ -392,14 +390,12 @@ JANET_CORE_FN(cfun_buffer_push_uint32,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        uint32_t data;
-        uint8_t bytes[4];
-    } u;
-    u.data = janet_getuinteger(argv, 2);
+    uint32_t data = janet_getuinteger(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse)
-        reverse_u32(u.bytes);
-    janet_buffer_push_u32(buffer, *(uint32_t *) u.bytes);
+        reverse_u32(bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
@@ -410,14 +406,12 @@ JANET_CORE_FN(cfun_buffer_push_uint64,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        uint64_t data;
-        uint8_t bytes[8];
-    } u;
-    u.data = janet_getuinteger64(argv, 2);
+    uint64_t data = janet_getuinteger64(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse)
-        reverse_u64(u.bytes);
-    janet_buffer_push_u64(buffer, *(uint64_t *) u.bytes);
+        reverse_u64(bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
@@ -428,14 +422,12 @@ JANET_CORE_FN(cfun_buffer_push_float32,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        float data;
-        uint8_t bytes[4];
-    } u;
-    u.data = (float) janet_getnumber(argv, 2);
+    float data = (float) janet_getnumber(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse)
-        reverse_u32(u.bytes);
-    janet_buffer_push_u32(buffer, *(uint32_t *) u.bytes);
+        reverse_u32(bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
@@ -446,14 +438,12 @@ JANET_CORE_FN(cfun_buffer_push_float64,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        double data;
-        uint8_t bytes[8];
-    } u;
-    u.data = janet_getnumber(argv, 2);
+    double data = janet_getnumber(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse)
-        reverse_u64(u.bytes);
-    janet_buffer_push_u64(buffer, *(uint64_t *) u.bytes);
+        reverse_u64(bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
diff --git a/src/core/os.c b/src/core/os.c
index 18e01b15..d7ffe6da 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -174,6 +174,8 @@ JANET_CORE_FN(os_arch,
               "* :riscv64\n\n"
               "* :sparc\n\n"
               "* :wasm\n\n"
+              "* :s390\n\n"
+              "* :s390x\n\n"
               "* :unknown\n") {
     janet_fixarity(argc, 0);
     (void) argv;
@@ -200,6 +202,10 @@ JANET_CORE_FN(os_arch,
     return janet_ckeywordv("ppc");
 #elif (defined(__ppc64__) || defined(_ARCH_PPC64) || defined(_M_PPC))
     return janet_ckeywordv("ppc64");
+#elif (defined(__s390x__))
+    return janet_ckeywordv("s390x");
+#elif (defined(__s390__))
+    return janet_ckeywordv("s390");
 #else
     return janet_ckeywordv("unknown");
 #endif