diff --git a/GNUmakefile b/GNUmakefile
index 7fb7169..b491a57 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -225,6 +225,12 @@ havesigio.h: trysigio.c
 	if $(DIET) $(CC) $(CFLAGS) -c trysigio.c >/dev/null 2>&1; then echo "#define HAVE_SIGIO"; fi > $@
 	-rm -f trysigio.o
 
+havealloca.h: tryalloca.c
+	-rm -f $@
+	echo "#include <stdlib.h>" > $@
+	if $(DIET) $(CC) $(CFLAGS) -c tryalloca.c >/dev/null 2>&1; then echo "#include <alloca.h>"; fi >> $@
+	-rm -f tryalloca.o
+
 iopause.h: iopause.h1 iopause.h2 trypoll.c
 	-rm -f $@
 	if $(DIET) $(CC) $(CFLAGS) -o t trypoll.c >/dev/null 2>&1; then cp iopause.h2 iopause.h; else cp iopause.h1 iopause.h; fi
diff --git a/Makefile b/Makefile
index c41a56a..b5671e6 100644
--- a/Makefile
+++ b/Makefile
@@ -585,7 +585,7 @@ uninstall:
 	rm -f $(patsubst %.3,$(MAN3DIR)/%.3,$(notdir $(wildcard */*.3)))
 	rm -f $(LIBDIR)/libowfat.a
 
-VERSION=libowfat-0.19
+VERSION=libowfat-0.20
 CURNAME=libowfat-0.19
 
 tar: clean rename
@@ -654,6 +654,12 @@ havesigio.h: trysigio.c
 	if $(DIET) $(CC) $(CFLAGS) -c trysigio.c >/dev/null 2>&1; then echo "#define HAVE_SIGIO"; fi > $@
 	-rm -f trysigio.o
 
+havealloca.h: tryalloca.c
+	-rm -f $@
+	echo "#include <stdlib.h>" > $@
+	if $(DIET) $(CC) $(CFLAGS) -c tryalloca.c >/dev/null 2>&1; then echo "#include <alloca.h>"; fi >> $@
+	-rm -f tryalloca.o
+
 iopause.h: iopause.h1 iopause.h2 trypoll.c
 	-rm -f $@
 	if $(DIET) $(CC) $(CFLAGS) -o t trypoll.c >/dev/null 2>&1; then cp iopause.h2 iopause.h; else cp iopause.h1 iopause.h; fi
diff --git a/havealloca.h b/havealloca.h
index 369fdba..4118018 100644
--- a/havealloca.h
+++ b/havealloca.h
@@ -1,3 +1,2 @@
-#if defined(__linux__) || defined(_SGI_SOURCE) || defined(__hpux__) || defined(__sun__)
+#include <stdlib.h>
 #include <alloca.h>
-#endif
diff --git a/tryalloca.c b/tryalloca.c
new file mode 100644
index 0000000..8b15ea3
--- /dev/null
+++ b/tryalloca.c
@@ -0,0 +1,6 @@
+#include <stdlib.h>
+#include <alloca.h>
+
+main() {
+  char* c=alloca(23);
+}