diff --git a/libguile/gc.h b/libguile/gc.h
index 15e372c9e..431e3ad44 100644
--- a/libguile/gc.h
+++ b/libguile/gc.h
@@ -74,11 +74,11 @@ typedef scm_cell * SCM_CELLPTR;
  *  pointers to scm_vector elts, functions, &c are not munged.
  */
 #ifdef _UNICOS
-    #define SCM2PTR(x) ((SCM_CELLPTR) (SCM_UNPACK (x) >> 3))
-    #define PTR2SCM(x) (SCM_PACK (((scm_bits_t) (x)) << 3))
+#  define SCM2PTR(x) ((SCM_CELLPTR) (SCM_UNPACK (x) >> 3))
+#  define PTR2SCM(x) (SCM_PACK (((scm_bits_t) (x)) << 3))
 #else
-    #define SCM2PTR(x) ((SCM_CELLPTR) (SCM_UNPACK (x)))
-    #define PTR2SCM(x) (SCM_PACK ((scm_bits_t) (x)))
+#  define SCM2PTR(x) ((SCM_CELLPTR) (SCM_UNPACK (x)))
+#  define PTR2SCM(x) (SCM_PACK ((scm_bits_t) (x)))
 #endif /* def _UNICOS */
 
 
diff --git a/libguile/tags.h b/libguile/tags.h
index 7fbe7989e..ed1f6a71a 100644
--- a/libguile/tags.h
+++ b/libguile/tags.h
@@ -66,23 +66,23 @@ typedef long scm_bits_t;
 #if (SCM_DEBUG_TYPING_STRICTNESS == 1)
     typedef union { struct { scm_bits_t n; } n; } SCM;
     static SCM scm_pack(scm_bits_t b) { SCM s; s.n.n = b; return s; }
-    #define SCM_UNPACK(x) ((x).n.n)
-    #define SCM_PACK(x) (scm_pack ((scm_bits_t) (x)))
+#   define SCM_UNPACK(x) ((x).n.n)
+#   define SCM_PACK(x) (scm_pack ((scm_bits_t) (x)))
 #elif defined (SCM_VOIDP_TEST)
 /* This is the default, which provides an intermediate level of compile time
  * type checking while still resulting in very efficient code.
  */
     typedef void * SCM;
-    #define SCM_UNPACK(x) ((scm_bits_t) (x))
-    #define SCM_PACK(x) ((SCM) (x))
+#   define SCM_UNPACK(x) ((scm_bits_t) (x))
+#   define SCM_PACK(x) ((SCM) (x))
 #else
 /* This should be used as a fall back solution for machines on which casting
  * to a pointer may lead to loss of bit information, e. g. in the three least
  * significant bits.
  */
     typedef scm_bits_t SCM;
-    #define SCM_UNPACK(x) (x)
-    #define SCM_PACK(x) ((scm_bits_t) (x))
+#   define SCM_UNPACK(x) (x)
+#   define SCM_PACK(x) ((scm_bits_t) (x))
 #endif