diff --git a/CMake/CurlTests.c b/CMake/CurlTests.c
index ac959f3406..ab244ac393 100644
--- a/CMake/CurlTests.c
+++ b/CMake/CurlTests.c
@@ -513,7 +513,7 @@ void check(char c) {}
 int
 main () {
   char buffer[1024];
-  // This will not compile if strerror_r does not return a char*
+  /* This will not compile if strerror_r does not return a char* */
   check(strerror_r(EACCES, buffer, sizeof(buffer))[0]);
   return 0;
 }
@@ -522,13 +522,13 @@ main () {
 #include <string.h>
 #include <errno.h>
 
-// float, because a pointer can't be implicitly cast to float
+/* float, because a pointer can't be implicitly cast to float */
 void check(float f) {}
 
 int
 main () {
   char buffer[1024];
-  // This will not compile if strerror_r does not return an int
+  /* This will not compile if strerror_r does not return an int */
   check(strerror_r(EACCES, buffer, sizeof(buffer)));
   return 0;
 }