diff --git a/simgear/misc/test_macros.hxx b/simgear/misc/test_macros.hxx
index 969ce5c6..c063dc3a 100644
--- a/simgear/misc/test_macros.hxx
+++ b/simgear/misc/test_macros.hxx
@@ -15,7 +15,7 @@
 #define SG_CHECK_EQUAL(a, b) \
     if ( !((a) == (b)) )  { \
         std::cerr << "failed: " << #a << " == " << #b << std::endl; \
-        std::cerr << "\tgot '" << a << "' and '" << b << "'" << std::endl; \
+        std::cerr << "\tgot '" << (a) << "' and '" << (b) << "'" << std::endl; \
         std::cerr << "\tat " << __FILE__ << ":" << __LINE__ << std::endl; \
         exit(1); \
     }
@@ -23,15 +23,15 @@
 #define SG_CHECK_EQUAL_EP(a, b) \
     if (std::fabs((a) - (b)) > SG_EPSILON)  { \
         std::cerr << "failed: " << #a << " ~= " << #b << std::endl; \
-        std::cerr << "\tgot '" << a << "' and '" << b << "'" << std::endl; \
+        std::cerr << "\tgot '" << (a) << "' and '" << (b) << "'" << std::endl; \
         std::cerr << "\tat " << __FILE__ << ":" << __LINE__ << std::endl; \
         exit(1); \
     }
 
 #define SG_CHECK_EQUAL_EP2(a, b, ep) \
-    if (std::fabs((a) - (b)) > ep)  { \
+  if (std::fabs((a) - (b)) > (ep))  {                               \
         std::cerr << "failed: " << #a << " ~= " << #b << std::endl; \
-        std::cerr << "\tgot '" << a << "' and '" << b << "'" << std::endl; \
+        std::cerr << "\tgot '" << (a) << "' and '" << (b) << "'" << std::endl; \
         std::cerr << "\tat " << __FILE__ << ":" << __LINE__ << std::endl; \
         exit(1); \
     }
@@ -39,7 +39,7 @@
 #define SG_CHECK_NE(a, b) \
     if ( !((a) != (b)) )  { \
         std::cerr << "failed: " << #a << " != " << #b << std::endl; \
-        std::cerr << "\tgot '" << a << "' and '" << b << "'" << std::endl; \
+        std::cerr << "\tgot '" << (a) << "' and '" << (b) << "'" << std::endl; \
         std::cerr << "\tat " << __FILE__ << ":" << __LINE__ << std::endl; \
         exit(1); \
     }
@@ -47,7 +47,7 @@
 #define SG_CHECK_LT(a, b) \
     if ( !((a) < (b)) )  { \
         std::cerr << "failed: " << #a << " < " << #b << std::endl; \
-        std::cerr << "\tgot '" << a << "' and '" << b << "'" << std::endl; \
+        std::cerr << "\tgot '" << (a) << "' and '" << (b) << "'" << std::endl; \
         std::cerr << "\tat " << __FILE__ << ":" << __LINE__ << std::endl; \
         exit(1); \
     }
@@ -55,7 +55,7 @@
 #define SG_CHECK_LE(a, b) \
     if ( !((a) <= (b)) )  { \
         std::cerr << "failed: " << #a << " <= " << #b << std::endl; \
-        std::cerr << "\tgot '" << a << "' and '" << b << "'" << std::endl; \
+        std::cerr << "\tgot '" << (a) << "' and '" << (b) << "'" << std::endl; \
         std::cerr << "\tat " << __FILE__ << ":" << __LINE__ << std::endl; \
         exit(1); \
     }
@@ -63,7 +63,7 @@
 #define SG_CHECK_GT(a, b) \
     if ( !((a) > (b)) )  { \
         std::cerr << "failed: " << #a << " > " << #b << std::endl; \
-        std::cerr << "\tgot '" << a << "' and '" << b << "'" << std::endl; \
+        std::cerr << "\tgot '" << (a) << "' and '" << (b) << "'" << std::endl; \
         std::cerr << "\tat " << __FILE__ << ":" << __LINE__ << std::endl; \
         exit(1); \
     }
@@ -71,7 +71,7 @@
 #define SG_CHECK_GE(a, b) \
     if ( !((a) >= (b)) )  { \
         std::cerr << "failed: " << #a << " >= " << #b << std::endl; \
-        std::cerr << "\tgot '" << a << "' and '" << b << "'" << std::endl; \
+        std::cerr << "\tgot '" << (a) << "' and '" << (b) << "'" << std::endl; \
         std::cerr << "\tat " << __FILE__ << ":" << __LINE__ << std::endl; \
         exit(1); \
     }