diff --git a/vvp/vpip_bin.cc b/vvp/vpip_bin.cc
index 0deff0327..ecbcd9eb6 100644
--- a/vvp/vpip_bin.cc
+++ b/vvp/vpip_bin.cc
@@ -35,7 +35,7 @@ void vpip_bin_str_to_vec4(vvp_vector4_t&vec4, const char*buf)
       unsigned skip_chars = 0;
       const char*tbuf = buf;
 	/* Find the number of non-numeric characters. */
-      while (tbuf = strpbrk(tbuf, "-_")) {
+      while ((tbuf = strpbrk(tbuf, "-_"))) {
 	    skip_chars += 1;
 	    tbuf += 1;
       }
diff --git a/vvp/vpip_hex.cc b/vvp/vpip_hex.cc
index cd7004ebd..3846ac235 100644
--- a/vvp/vpip_hex.cc
+++ b/vvp/vpip_hex.cc
@@ -36,7 +36,7 @@ void vpip_hex_str_to_vec4(vvp_vector4_t&val, const char*str)
       unsigned skip_chars = 0;
       const char*tstr = str;
 	/* Find the number of non-numeric characters. */
-      while (tstr = strpbrk(tstr, "-_")) {
+      while ((tstr = strpbrk(tstr, "-_"))) {
 	    skip_chars += 1;
 	    tstr += 1;
       }
diff --git a/vvp/vpip_oct.cc b/vvp/vpip_oct.cc
index 90efed18a..0b28e102e 100644
--- a/vvp/vpip_oct.cc
+++ b/vvp/vpip_oct.cc
@@ -36,7 +36,7 @@ void vpip_oct_str_to_vec4(vvp_vector4_t&val, const char*str)
       unsigned skip_chars = 0;
       const char*tstr = str;
 	/* Find the number of non-numeric characters. */
-      while (tstr = strpbrk(tstr, "-_")) {
+      while ((tstr = strpbrk(tstr, "-_"))) {
 	    skip_chars += 1;
 	    tstr += 1;
       }