diff --git a/src/extern/err.c b/src/extern/err.c
index 7c5587d0..bfeced2b 100644
--- a/src/extern/err.c
+++ b/src/extern/err.c
@@ -30,9 +30,9 @@ extern char *progname;
 
 void rgbds_vwarn(const char *fmt, va_list ap)
 {
-	fprintf (stderr, "%s:warning", progname);
+	fprintf (stderr, "%s: warning", progname);
 	if (fmt) {
-		fputs (":", stderr);
+		fputs (": ", stderr);
 		vfprintf(stderr, fmt, ap);
 	}
 	putc('\n', stderr);
@@ -41,9 +41,9 @@ void rgbds_vwarn(const char *fmt, va_list ap)
 
 void rgbds_vwarnx(const char *fmt, va_list ap)
 {
-	fprintf (stderr, "%s:warning", progname);
+	fprintf (stderr, "%s: warning", progname);
 	if (fmt) {
-		fputs (":", stderr);
+		fputs (": ", stderr);
 		vfprintf(stderr, fmt, ap);
 	}
 	putc('\n', stderr);
@@ -51,9 +51,9 @@ void rgbds_vwarnx(const char *fmt, va_list ap)
 
 noreturn void rgbds_verr(int status, const char *fmt, va_list ap)
 {
-	fprintf (stderr, "%s:error", progname);
+	fprintf (stderr, "%s: error", progname);
 	if (fmt) {
-		fputs (":", stderr);
+		fputs (": ", stderr);
 		vfprintf(stderr, fmt, ap);
 	}
 	putc('\n', stderr);
@@ -62,9 +62,9 @@ noreturn void rgbds_verr(int status, const char *fmt, va_list ap)
 
 noreturn void rgbds_verrx(int status, const char *fmt, va_list ap)
 {
-	fprintf (stderr, "%s:error", progname);
+	fprintf (stderr, "%s: error", progname);
         if (fmt) {
-                fputs (":", stderr);
+                fputs (": ", stderr);
                 vfprintf(stderr, fmt, ap);
         }
 	putc('\n', stderr);
diff --git a/test/asm/undefined-dot.out b/test/asm/undefined-dot.out
index aeb8fd05..e1e4ffb6 100644
--- a/test/asm/undefined-dot.out
+++ b/test/asm/undefined-dot.out
@@ -1,3 +1,3 @@
 ERROR: undefined-dot.asm(3):
 	'.' not defined
-rgbasm:error:Assembly aborted in pass 2 (1 errors)!
+rgbasm: error: Assembly aborted in pass 2 (1 errors)!
diff --git a/test/link/bank-numbers.out b/test/link/bank-numbers.out
index a54b4d30..427fe8b0 100644
--- a/test/link/bank-numbers.out
+++ b/test/link/bank-numbers.out
@@ -1,2 +1,2 @@
-rgblink:warning:Trying to calculate BANK() of label in HRAM.
-rgblink:warning:Trying to calculate BANK() of label in OAM.
+rgblink: warning: Trying to calculate BANK() of label in HRAM.
+rgblink: warning: Trying to calculate BANK() of label in OAM.