diff --git a/configure.ac b/configure.ac
index 5b0ce95..92ff82c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -74,6 +74,12 @@ AC_CHECK_FUNCS([\
 ])
 AC_CHECK_DECL([strndupa])
 
+AC_CHECK_FUNCS([fpclassify], [],
+	[AC_CHECK_LIB([m], [fpclassify], [MATH_LIBS="-lm"])]
+	[AC_CHECK_LIB([m], [__fpclassify], [MATH_LIBS="-lm"])]
+)
+AC_SUBST([MATH_LIBS])
+
 AS_IF([test "x$ac_cv_func_open_memstream" = "xyes" && test "x$ac_cv_have_decl_strndupa" == "xyes"], [
 	build_mustach=yes
 	AC_DEFINE([BUILD_MUSTACH], [1], [build mustach support])
diff --git a/src/Makemodule.am b/src/Makemodule.am
index c072af3..e1c75f5 100644
--- a/src/Makemodule.am
+++ b/src/Makemodule.am
@@ -4,7 +4,7 @@ bin_PROGRAMS = dhcpd-pools
 AC_PROG_RANLIB = resolv
 AM_CPPFLAGS = -I$(top_srcdir)/src -I$(top_srcdir)/lib -I$(top_builddir)/lib
 
-dhcpd_pools_LDADD = $(top_builddir)/lib/libdhcpd_pools.la
+dhcpd_pools_LDADD = $(top_builddir)/lib/libdhcpd_pools.la $(MATH_LIBS)
 
 dhcpd_pools_SOURCES = \
 	src/analyze.c \
diff --git a/src/mustach-dhcpd-pools.c b/src/mustach-dhcpd-pools.c
index 1019452..8fa1bec 100644
--- a/src/mustach-dhcpd-pools.c
+++ b/src/mustach-dhcpd-pools.c
@@ -64,10 +64,9 @@ static int must_enter(void *closure, const char *name);
 static int must_leave(void *closure);
 
 /* This can be called when template is invalid end put happens before enter. */
-int must_put_err(void *closure __attribute__ ((unused)),
-		 const char *name __attribute__ ((unused)),
-		 int escape __attribute__ ((unused)),
-		 FILE *file __attribute__ ((unused)))
+static int must_put_err(void *closure __attribute__ ((unused)),
+			const char *name __attribute__ ((unused)),
+			int escape __attribute__ ((unused)), FILE *file __attribute__ ((unused)))
 {
 	return MUSTACH_ERROR_SYSTEM;
 }
diff --git a/src/output.c b/src/output.c
index 21d67f4..ebd841f 100644
--- a/src/output.c
+++ b/src/output.c
@@ -106,22 +106,21 @@ int shnet_output_helper(struct conf_t *state, struct output_helper_t *oh,
 {
 	/* counts and calculations */
 	oh->tc = shared_p->touched + shared_p->used;
-	if (shared_p->available == 0) {
+	if (fpclassify(shared_p->available) == FP_ZERO) {
 		oh->percent = NAN;
 		oh->tcp = NAN;
 		oh->bup = NAN;
-	} else {
-		oh->percent = (double)(100 * shared_p->used) / shared_p->available;
-		oh->tcp =
-		    (double)((100 * (shared_p->touched + shared_p->used)) / shared_p->available);
-		if (state->backups_found == 1) {
-			oh->bup = (double)(100 * shared_p->backups) / shared_p->available;
-		}
-	}
-	/* set status */
-	if (oh->percent == NAN)
 		oh->status = STATUS_SUPPRESSED;
-	else if (shared_p->available <= state->minsize)
+		return 0;
+	}
+
+	oh->percent = (double)(100 * shared_p->used) / shared_p->available;
+	oh->tcp = (double)((100 * (shared_p->touched + shared_p->used)) / shared_p->available);
+	if (state->backups_found == 1)
+		oh->bup = (double)(100 * shared_p->backups) / shared_p->available;
+
+	/* set status */
+	if (shared_p->available <= state->minsize)
 		oh->status = STATUS_IGNORED;
 	else if (state->critical < oh->percent && shared_p->used < state->crit_count)
 		oh->status = STATUS_CRIT;
@@ -503,18 +502,18 @@ static int output_json(struct conf_t *state, const int print_mac_addreses)
 			fprintf(outfile, "\"used\":%g, ", shared_p->used);
 			fprintf(outfile, "\"touched\":%g, ", shared_p->touched);
 			fprintf(outfile, "\"free\":%g, ", shared_p->available - shared_p->used);
-			if (shared_p->available == 0)
+			if (fpclassify(shared_p->available) == FP_ZERO)
 				fprintf(outfile, "\"percent\":\"%g\", ", oh.percent);
 			else
 				fprintf(outfile, "\"percent\":%g, ", oh.percent);
 			fprintf(outfile, "\"touch_count\":%g, ", oh.tc);
-			if (shared_p->available == 0)
+			if (fpclassify(shared_p->available) == FP_ZERO)
 				fprintf(outfile, "\"touch_percent\":\"%g\", ", oh.tcp);
 			else
 				fprintf(outfile, "\"touch_percent\":%g, ", oh.tcp);
 			if (state->backups_found == 1) {
 				fprintf(outfile, "\"backup_count\":%g, ", shared_p->backups);
-				if (shared_p->available == 0)
+				if (fpclassify(shared_p->available) == FP_ZERO)
 					fprintf(outfile, "\"backup_percent\":\"%g\", ", oh.bup);
 				else
 					fprintf(outfile, "\"backup_percent\":%g, ", oh.bup);
diff --git a/src/sort.c b/src/sort.c
index 5911a20..4fdb4e0 100644
--- a/src/sort.c
+++ b/src/sort.c
@@ -252,7 +252,7 @@ comparer_t field_selector(char c)
  * \param right The right side of the merge sort.
  * \return Relevant for merge sort decision.
  */
-int merge(struct conf_t *state, struct range_t *restrict left, struct range_t *restrict right)
+static int merge(struct conf_t *state, struct range_t *restrict left, struct range_t *restrict right)
 {
 	struct output_sort *p;
 	int ret;
@@ -282,13 +282,12 @@ void mergesort_ranges(struct conf_t *state, struct range_t *restrict orig, unsig
 	unsigned int left, i, u_right;
 	int s_right;
 	struct range_t hold;
+	/* Merge sort split size */
+	static const unsigned int MIN_MERGE_SIZE = 8;
 
 	if (temp == NULL)
 		temp = xmalloc(sizeof(struct range_t) * size);
 
-	/* Merge sort split size */
-	static const unsigned int MIN_MERGE_SIZE = 8;
-
 	if (size < MIN_MERGE_SIZE) {
 		for (left = 0; left < size; left++) {
 			hold = *(orig + left);