diff --git a/configure.ac b/configure.ac
index e72e70424..b986567a0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -47,6 +47,7 @@ AC_SUBST(DBUS_GLIB_MINIMUM)
 
 AC_PROG_CC
 AC_PROG_CXX
+AC_C_INLINE
 if test "x$GCC" = "xyes" ; then
     CFLAGS="-Wall -Wformat-security -W -Wmissing-prototypes -Wdeclaration-after-statement"
     CXXFLAGS="-Wall -Wformat-security -W"
diff --git a/libtransmission/net.h b/libtransmission/net.h
index 1953557ff..4585aea09 100644
--- a/libtransmission/net.h
+++ b/libtransmission/net.h
@@ -87,7 +87,7 @@ void tr_normalizeV4Mapped( tr_address * const addr );
 
 void tr_suspectAddress( const tr_address * a, const char * source );
 
-#define tr_isAddress(a) ( ((a)!=NULL) && ( (a)->type==TR_AF_INET || (a)->type==TR_AF_INET6 ) )
+static inline tr_bool tr_isAddress( const tr_address * a ) { return ( a != NULL ) && ( a->type==TR_AF_INET || a->type==TR_AF_INET6 ); }
 
 typedef struct tr_net_af_support
 {
diff --git a/libtransmission/transmission.h b/libtransmission/transmission.h
index 24ff8afdc..c808941dc 100644
--- a/libtransmission/transmission.h
+++ b/libtransmission/transmission.h
@@ -1415,7 +1415,7 @@ void tr_torrentSetDoneDate( tr_torrent  * torrent,
                             time_t        doneDate );
 
 /** @brief Sanity checker to test that the direction is TR_UP or TR_DOWN */
-#define tr_isDirection(d) (((d)==TR_UP) || ((d)==TR_DOWN))
+static inline tr_bool tr_isDirection( tr_direction d ) { return d==TR_UP || d==TR_DOWN; }
 
 /** @} */