diff --git a/configure.ac b/configure.ac
index d75422d8..78250621 100644
--- a/configure.ac
+++ b/configure.ac
@@ -298,6 +298,11 @@ fi
 if test "$enable_static" = yes; then
    AC_SEARCH_LIBS([Gpm_GetEvent], [gpm])
 fi
+if test "$my_htop_platform" = "solaris"; then
+   # On OmniOS /usr/include/sys/regset.h redefines ERR to 13 - \r, breaking the Enter key.
+   # Since ncruses macros use the ERR macro, we can not use another name.
+   AC_DEFINE([ERR], [(-1)], [Predefine ncurses macro.])
+fi
 
 
 AC_ARG_ENABLE([hwloc],
diff --git a/solaris/Platform.h b/solaris/Platform.h
index cf94fbb3..f83c4d1c 100644
--- a/solaris/Platform.h
+++ b/solaris/Platform.h
@@ -12,7 +12,15 @@ in the source distribution for its full text.
 #include "config.h" // IWYU pragma: keep
 
 #include <kstat.h>
+
+/* On OmniOS /usr/include/sys/regset.h redefines ERR to 13 - \r, breaking the Enter key.
+ * Since ncruses macros use the ERR macro, we can not use another name.
+ */
+#undef ERR
 #include <libproc.h>
+#undef ERR
+#define ERR (-1)
+
 #include <signal.h>
 #include <stdbool.h>
 
diff --git a/solaris/SolarisProcess.h b/solaris/SolarisProcess.h
index 0b12aa0f..07b889c0 100644
--- a/solaris/SolarisProcess.h
+++ b/solaris/SolarisProcess.h
@@ -12,7 +12,14 @@ in the source distribution for its full text.
 
 #include <zone.h>
 #include <sys/proc.h>
+
+/* On OmniOS /usr/include/sys/regset.h redefines ERR to 13 - \r, breaking the Enter key.
+ * Since ncruses macros use the ERR macro, we can not use another name.
+ */
+#undef ERR
 #include <libproc.h>
+#undef ERR
+#define ERR (-1)
 
 #include "Settings.h"