diff --git a/configure.ac b/configure.ac
index 827b70d..e8dc082 100644
--- a/configure.ac
+++ b/configure.ac
@@ -128,14 +128,29 @@ then
 	CFLAGS="$CFLAGS -msse2"
 fi
 
+
 AC_ARG_ENABLE([intfilter],
 	[AS_HELP_STRING([--enable-intfilter],
-		[use 64bit integers for filtering. faster but limits filter length @<:@default=no@:>@])],
+		[use 64-bit integers for filtering. faster but limits filter length to 12 @<:@default=no@:>@])],
 	[], [enable_intfilter=no]
 )
-if test "x$enable_intfilter" = "xyes"
+AC_ARG_ENABLE([intfilter32],
+	[AS_HELP_STRING([--enable-intfilter32],
+		[use 32-bit integers for filtering. even faster on 32-bit machines but limits filter length to 6 @<:@default=no@:>@])],
+	[], [enable_intfilter32=no]
+)
+if test "x$enable_intfilter32" = "xyes"
 then
-	MYDEFS="$MYDEFS -DINTFILTER"
+	if test "x$enable_intfilter" = "xyes"
+	then
+		AC_MSG_WARN([both intfilter and intfilter32 specified; using intfilter32])
+	fi
+	MYDEFS="$MYDEFS -DINTFILTER -DIFT=u32"
+else
+	if test "x$enable_intfilter" = "xyes"
+	then
+		MYDEFS="$MYDEFS -DINTFILTER"
+	fi
 fi
 
 AC_ARG_ENABLE([statistics],
diff --git a/main.c b/main.c
index cf46562..4f27090 100644
--- a/main.c
+++ b/main.c
@@ -74,8 +74,11 @@ struct binfilter {
 } ;
 
 #ifdef INTFILTER
+#ifndef IFT
+#define IFT u64
+#endif
 struct intfilter {
-	u64 f,m;
+	IFT f,m;
 } ;
 VEC_STRUCT(ifiltervec,struct intfilter) ifilters;
 #else
@@ -146,8 +149,8 @@ static void filters_add(const char *filter)
 	size_t ret, ret2;
 #ifdef INTFILTER
 	union intconv {
-		u64 i;
-		u8 b[8];
+		IFT i;
+		u8 b[sizeof(IFT)];
 	} fc,mc;
 #endif
 
@@ -161,7 +164,7 @@ static void filters_add(const char *filter)
 	if (!ret)
 		return;
 #ifdef INTFILTER
-	if (ret > 8)
+	if (ret > sizeof(IFT))
 #else
 	if (ret > PUBLIC_LEN)
 #endif
@@ -177,7 +180,7 @@ static void filters_add(const char *filter)
 	for (size_t i = 0;i < bf.len;++i)
 		mc.b[i] = 0xFF;
 	mc.b[bf.len] = bf.mask;
-	memcpy(fc.b,bf.f,8);
+	memcpy(fc.b,bf.f,sizeof(fc.b));
 	fc.i &= mc.i;
 	struct intfilter ifltr = {.f = fc.i,.m = mc.i};
 	VEC_FOR(ifilters,i) {
@@ -227,7 +230,7 @@ static size_t filters_count()
 #ifdef INTFILTER
 
 #define FILTERFOR(it) for (it = 0;it < VEC_LENGTH(ifilters);++it)
-#define MATCHFILTER(it,pk) ((*(u64 *)(pk) & VEC_BUF(ifilters,it).m) == VEC_BUF(ifilters,it).f)
+#define MATCHFILTER(it,pk) ((*(IFT *)(pk) & VEC_BUF(ifilters,it).m) == VEC_BUF(ifilters,it).f)
 
 #else
 
@@ -273,7 +276,7 @@ static void printfilters()
 #ifdef INTFILTER
 		size_t len = 0;
 		u8 *imraw = (u8 *)&VEC_BUF(ifilters,i).m;
-		while (len < 8 && imraw[len] != 0x00) ++len;
+		while (len < sizeof(IFT) && imraw[len] != 0x00) ++len;
 		u8 mask = imraw[len-1];
 		u8 *ifraw = (u8 *)&VEC_BUF(ifilters,i).f;
 #else