diff --git a/test/crypto_kem/functest.c b/test/crypto_kem/functest.c
index a2721e86..74cef3f6 100644
--- a/test/crypto_kem/functest.c
+++ b/test/crypto_kem/functest.c
@@ -50,8 +50,15 @@ static int check_canary(const uint8_t *d) {
         return -1;                                \
     }
 
-#define DEFER(x) x
-#define NAMESPACE_CHECK DEFER(NAMESPACE(API_H))
+// https://stackoverflow.com/a/55243651/248065
+#define MY_TRUTHY_VALUE_X 1
+#define CAT(x,y) CAT_(x,y)
+#define CAT_(x,y) x##y
+#define HAS_NAMESPACE(x) CAT(CAT(MY_TRUTHY_VALUE_,CAT(PQCLEAN_NAMESPACE,CAT(_,x))),X)
+
+#if !HAS_NAMESPACE(API_H)
+#error "namespace not properly defined for header guard"
+#endif
 
 static int test_keys(void) {
     /*
@@ -200,9 +207,8 @@ static int test_invalid_ciphertext(void) {
 }
 
 int main(void) {
-    // these two will trigger compiler errors
+    // Check if CRYPTO_ALGNAME is printable
     puts(CRYPTO_ALGNAME);
-    NAMESPACE_CHECK;
 
     int result = 0;
     result += test_keys();
diff --git a/test/crypto_sign/functest.c b/test/crypto_sign/functest.c
index 2eaf8f5c..57e9e0da 100644
--- a/test/crypto_sign/functest.c
+++ b/test/crypto_sign/functest.c
@@ -51,8 +51,16 @@ static int check_canary(const uint8_t *d) {
         return -1;                                \
     }
 
-#define DEFER(x) x
-#define NAMESPACE_CHECK DEFER(NAMESPACE(API_H))
+// https://stackoverflow.com/a/55243651/248065
+#define MY_TRUTHY_VALUE_X 1
+#define CAT(x,y) CAT_(x,y)
+#define CAT_(x,y) x##y
+#define HAS_NAMESPACE(x) CAT(CAT(MY_TRUTHY_VALUE_,CAT(PQCLEAN_NAMESPACE,CAT(_,x))),X)
+
+#if !HAS_NAMESPACE(API_H)
+#error "namespace not properly defined for header guard"
+#endif
+
 
 static int test_sign(void) {
     /*
@@ -163,10 +171,8 @@ static int test_wrong_pk(void) {
 }
 
 int main(void) {
-    // these two will generate compile errors
+    // check if CRYPTO_ALGNAME is printable
     puts(CRYPTO_ALGNAME);
-    NAMESPACE_CHECK;
-
     int result = 0;
     result += test_sign();
     result += test_wrong_pk();