diff --git a/meson.build b/meson.build
index 09c2037..69cfa4f 100644
--- a/meson.build
+++ b/meson.build
@@ -46,7 +46,8 @@ endif
 
 add_global_arguments('-D_GNU_SOURCE', language: 'c')
 
-warns = [ 'all', 'extra', 'no-unused-parameter', 'nonnull', 'shadow', 'implicit-fallthrough' ]
+warns = [ 'all', 'extra', 'no-unused-parameter', 'nonnull', 'shadow',
+          'implicit-fallthrough', 'no-unknown-warning-option' ]
 foreach w : warns
 	if cc.has_argument('-W'+w)
 		add_global_arguments('-W'+w, language: 'c')
diff --git a/src/log.c b/src/log.c
index e3f50bd..2fa4720 100644
--- a/src/log.c
+++ b/src/log.c
@@ -72,7 +72,7 @@ static attr_const const char *log_level_to_string(enum log_level level) {
 	case LOG_LEVEL_WARN: return "WARN";
 	case LOG_LEVEL_ERROR: return "ERROR";
 	case LOG_LEVEL_FATAL: return "FATAL ERROR";
-	default: assert(false);
+	default: return "????";
 	}
 }
 
@@ -254,7 +254,7 @@ const char *terminal_colorize_begin(enum log_level level) {
 	case LOG_LEVEL_WARN: return ANSI("33");
 	case LOG_LEVEL_ERROR: return ANSI("31;1");
 	case LOG_LEVEL_FATAL: return ANSI("30;103;1");
-	default: assert(false);
+	default: return "";
 	}
 }
 
diff --git a/src/string_utils.c b/src/string_utils.c
index 6b3a8d2..26b1c5b 100644
--- a/src/string_utils.c
+++ b/src/string_utils.c
@@ -7,6 +7,15 @@
 #include "string_utils.h"
 #include "utils.h"
 
+#pragma GCC diagnostic push
+
+// gcc warns about legitimate strncpy in mstrjoin and mstrextend
+// strncpy(str, src1, len1) intentional truncates the null byte from src1.
+// strncpy(str+len1, src2, len2) uses bound depends on the source argument,
+// but str is allocated with len1+len2+1, so this strncpy can't overflow
+#pragma GCC diagnostic ignored "-Wstringop-truncation"
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
+
 /**
  * Allocate the space and join two strings.
  */
@@ -41,6 +50,8 @@ void mstrextend(char **psrc1, const char *src2) {
 	(*psrc1)[len - 1] = '\0';
 }
 
+#pragma GCC diagnostic pop
+
 /// Parse a floating point number of form (+|-)?[0-9]*(\.[0-9]*)
 double strtod_simple(const char *src, const char **end) {
   double neg = 1;