diff --git a/Makefile.unix b/Makefile.unix
index e78e61ec2..ce6b0b7b4 100644
--- a/Makefile.unix
+++ b/Makefile.unix
@@ -89,6 +89,7 @@ GTKCFLAGS := -std=c99 -Dgtk -Dnsgtk \
 	-D_BSD_SOURCE \
 	-D_XOPEN_SOURCE=600 \
 	-D_POSIX_C_SOURCE=200112L \
+	-D_NETBSD_SOURCE \
 	$(WARNFLAGS) -I. -g -O \
 	$(shell pkg-config --cflags libglade-2.0 gtk+-2.0 librsvg-2.0) \
 	$(shell xml2-config --cflags)
diff --git a/utils/utils.h b/utils/utils.h
index 0ddf62dc0..3a0417008 100644
--- a/utils/utils.h
+++ b/utils/utils.h
@@ -66,7 +66,7 @@ void regcomp_wrapper(regex_t *preg, const char *regex, int cflags);
 void unicode_transliterate(unsigned int c, char **r);
 char *human_friendly_bytesize(unsigned long bytesize);
 const char *rfc1123_date(time_t t);
-#ifndef _GNU_SOURCE
+#if !(defined(_GNU_SOURCE) || defined(__NetBSD__))
 char *strcasestr(const char *haystack, const char *needle);
 #endif
 unsigned int wallclock(void);